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  • About
      About Our Clinic

      Meet Dr. Peterson

      Get to know Dr. Ralph L. Peterson and the MacArthur Gastroenterology team, along with our approach to digestive and liver health care.

      Portrait of Dr. Ralph Peterson, gastroenterologist at MacArthur Gastroenterology in Oakland
      Dr. Ralph L. Peterson, MD

      Gastroenterologist

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      MacArthur Gastroenterology Inc.
      10520 MacArthur Blvd.
      Oakland, CA 94605

      (510) 562-7467

  • Services
      Our Services

      Care built around you

      Four ways we support your digestive and liver health, each with a dedicated page.

      Gastroenterology

      Comprehensive digestive health, screening, and treatment.

      Weight Management

      Physician-supervised weight loss, GLP-1 support, and coaching.

      MASLD / Fatty Liver Scanning

      Fast, non-invasive liver fat and stiffness screening.

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  • Weight Management

      Weight Management

      Patient celebrating progress in the Weight Management program
      Weight Management

      Lose weight. Feel better. Live healthier.

      A physician-supervised program combining medical evaluation, personalized coaching, and compounded GLP-1 support when clinically appropriate.

      Explore the program →
  • MASLD / Liver Scan

      MASLD / Liver Scan

      Liver scan procedure at MacArthur Gastroenterology
      MASLD / Fatty Liver

      A 10-minute scan that can change your outlook

      Our in-office ultrasound-based scan measures liver fat and stiffness in minutes, with no needles, no sedation, and results the same day.

      Learn about the liver scan →
  • Contact
      Contact Us

      We're here to help

      Reach our front desk directly, or send a message and our team will follow up.

      (510) 562-7467
      Call our front desk

      Send us a message
      Contact form, response within 1 business day

      10520 MacArthur Blvd., Oakland, CA 94605
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      Office Hours
      Monday:
      9:00 AM to 3:30 PM;
      3:30 PM to 6:00 PM by appointment only.
      Tuesday:
      7:30 AM to 3:30 PM;
      3:30 PM to 6:00 PM by appointment only.
      Wednesday:
      9:00 AM to 3:30 PM;
      3:30 PM to 6:00 PM by appointment only.
      Thursday:
      9:00 AM to 3:30 PM;
      3:30 PM to 6:00 PM by appointment only.
      Friday:
      9:00 AM to 2:00 PM;
      By appointment only.
      Saturday:
      9:00 AM to 2:00 PM;
      By appointment only.
      Sunday: Closed.
  • Make a Payment
      Billing

      Pay your bill securely online

      View your balance and make a payment anytime, no portal login required.

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      Billing questions: (510) 562-7467

  • Patient Portal
      What you can do in the portal
      • Message your care team securely
      • View lab and test results
      • Manage appointments and get reminders
      • Request prescription refills
      • Complete forms before your visit
      • Join telehealth visits and pay bills

      Click here for more info about the portal →

      Patients

      Access the MacArthur GI Patient Portal

      Message your care team, view test results, request refills, and manage appointments from your secure patient account.

      Access patient portal →

      New patient? Ask our front desk for portal access at your first visit.

Accessibility Statement

Last reviewed: October 29, 2026

MacArthur Gastroenterology Inc. (Mac GI) wants every patient to be able to learn about our services, book an appointment and get care with us. That includes people with disabilities, older adults and anyone who uses assistive technology.

Our goal

We aim to meet the Web Content Accessibility Guidelines (WCAG) 2.1, Level AA. These guidelines explain how to make websites easier to use for people who are blind or have low vision, are deaf or hard of hearing, or have motor, speech or cognitive disabilities.

What we do

  • Use clear headings and plain language so pages are easy to follow.
  • Add text descriptions to meaningful images.
  • Support keyboard navigation and visible focus outlines.
  • Use readable text sizes, strong color contrast and large buttons that are easy to tap.
  • Make our phone number a tap-to-call link on every page, so you can reach a person at any step.
  • Design pages to work on phones, tablets and computers, and with browser zoom.
  • Review our website for accessibility when we add or change pages.

Third-party tools

Some features on our website come from other companies, including our online booking calendar, secure payment checkout and maps. We choose these tools with care, but we do not fully control how accessible they are. If any of them is hard to use, call us and we will help you directly.

Booking by phone

You never need to use the website to book. Our team can schedule your appointment, answer questions about cost or insurance and explain how to prepare for your visit. Call (510) 562-7467.

Help at your visit

Let us know when you book if you need help during your visit. For example, tell us if you use a wheelchair or walker, have trouble lying flat or raising your arm, need someone to come with you, or have hearing or vision needs. We will do our best to make your visit comfortable.

If you have questions about parking or getting into our office, call us before your visit.

Language assistance

Ask our office about care in English, Spanish, Vietnamese, Cantonese, Mandarin, Tagalog or Arabic. Please let us know your preferred language when you book, so our staff can confirm what is available for your appointment.

Office hours

  • Monday: 9:00 AM to 3:30 PM, and 3:30 PM to 6:00 PM by appointment only
  • Tuesday: 7:30 AM to 3:30 PM, and 3:30 PM to 6:00 PM by appointment only
  • Wednesday: 9:00 AM to 3:30 PM, and 3:30 PM to 6:00 PM by appointment only
  • Thursday: 9:00 AM to 3:30 PM, and 3:30 PM to 6:00 PM by appointment only
  • Friday: 9:00 AM to 2:00 PM, by appointment only
  • Saturday: 9:00 AM to 2:00 PM, by appointment only
  • Sunday: Closed

Tell us about a problem

If something on our website is hard to use, please tell us. Let us know the page and what happened, and we will follow up with you as soon as we can.

MacArthur Gastroenterology Inc. (Mac GI)
10520 MacArthur Blvd., Oakland, CA 94605
Office: (510) 562-7467
Contact page

Explore our Weight Management, Liver Scan, and Concierge care programs.

View Our Services

Compassionate, preventive digestive and liver care for the Bay Area.

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  • About
  • Services
  • Weight Management
  • MASLD / Liver Scan
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Contact

10520 MacArthur Blvd.
Oakland, CA 94605

(510) 562-7467

Fax: (510) 227-6895

info@macarthurgi.com

Send us a message →

Office Hours

Monday:
9:00 AM to 3:30 PM;
3:30 PM to 6:00 PM by appointment only.
Tuesday:
7:30 AM to 3:30 PM;
3:30 PM to 6:00 PM by appointment only.
Wednesday:
9:00 AM to 3:30 PM;
3:30 PM to 6:00 PM by appointment only.
Thursday:
9:00 AM to 3:30 PM;
3:30 PM to 6:00 PM by appointment only.
Friday:
9:00 AM to 2:00 PM;
By appointment only.
Saturday:
9:00 AM to 2:00 PM;
By appointment only.
Sunday: Closed.

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