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Member Profile

Guillermo Ruiz Arguelles, MD, MACP

For Dr. Guillermo Ruiz Arguelles, a career as an internist and hematologist seemed like destiny. Thinking back, Dr. Ruiz amusingly admits that he "did not have very many choices to be anything other than a doctor."

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Officer Profiles

Ana María López, MD, FACP, and Andrew Dunn, MD, FACP

ACP is delighted to introduce our incoming ACP President and incoming Chair of the Board of Regents.

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About ACP

Who We Are

ACP is a national organization of internists, the largest medical-specialty organization, and second-largest physician group in the United States. Our 152,000 members include internists, internal medicine subspecialists, medical students, residents, and fellows.

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About Internal Medicine

Internal medicine physicians are specialists who apply scientific knowledge and clinical expertise to the diagnosis, treatment, and compassionate care of adults across the spectrum from health to complex illness.

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Chapters & Regions View a complete list

United States Chapters & Regions

The American College of Physicians acts locally through its chapters and regions. To learn more about chapter services, structure and operations, see our FAQ about chapters.

Canadian Chapters

All Provinces

The American College of Physicians acts locally through its chapters and regions. To learn more about chapter services, structure and operations, see our FAQ about chapters.

Latin American Chapters

The American College of Physicians acts locally through its chapters and regions. To learn more, see our FAQ about chapters.

Armed Forces Chapters

The American College of Physicians acts locally through its chapters and regions. To learn more, see our FAQ about chapters.

Additional International Chapters

The American College of Physicians acts locally through its chapters and regions. To learn more about chapter services, structure and operations, see our FAQ about chapters.


ACP International

For international medical students, graduates, and practicing physicians across the globe: Learn more about what ACP's diverse presence means to members in over 145 countries worldwide.


ACP Leadership

ACP is governed by an elected Board of Regents, which manages business and policy issues. The Board is advised by a network of ACP committees and by the ACP Board of Governors.

Awards and Masterships

ACP recognizes excellence and distinguished contributions to internal medicine. The College offers 23 national awards and a number of Masterships each year.


ACP Services

A set of resources for members interested in exploring how ACP is committed to supporting efforts that improve the practice of internal medicine.

Contact Us

Let us answer your questions. Contact our helpful member and customer service team today and let us help you in any way that we can.