Our Health Library information does not replace the advice of a doctor. Please be advised that this information is made available to assist our patients to learn more about their health. Our providers may not see and/or treat all topics found herein.

Rh factor

The surface of red blood cells contains markers that the immune system can recognize—one of these markers is the Rh factor (Rh [D] antigen). A person whose blood contains the Rh factor is Rh-positive (D); a person whose blood does not contain the Rh factor is Rh-negative (d).

Blood type contains information about the presence (+) or absence (–) of the Rh factor. Blood type is indicated by a letter (A, B, or O) and a symbol (+ or –). If a person has B negative (B–) blood, for example, that person is Rh-negative. A person with B positive blood (B+) is Rh-positive.

Current as of: May 1, 2026

Author: WebMD Ignite Staff

Clinical Review Board
All WebMD Ignite education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

News & Events

View All

Pelvic Changes in Your 40s No One Talks About

Your 40s can bring many changes to your body, and while topics like weight gain, muscle loss, and thinning hair often get attention,

Facebook

Phone

Schedule an Appointment Online