Main Content
Top of the page
Human blood is typed according to whether certain markers, called antigens, are present on the surface of red blood cells. The ABO system classifies blood as type A, B, AB, or O based on the presence or absence of the A and B antigens; the Rh system classifies blood as negative or positive based on the presence or absence of the Rh antigen (Rh factor).
If red blood cells have:
Rh blood typing determines the presence (+) or absence (–) of the Rh factor. If red blood cells:
Current as of: September 8, 2022
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Anne C. Poinier MD - Internal Medicine & Adam Husney MD - Family Medicine & Martin J. Gabica MD - Family Medicine & Brian Leber MDCM, FRCPC - Hematology
This information does not replace the advice of a doctor. Healthwise, Incorporated, disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Learn how we develop our content.