Check your medical records from past doctor visits, blood donations, surgeries, pregnancies, or hospital stays
Ask your parents or close relatives if they know your blood type
Contact your primary care doctor or clinic and request your blood type from your chart
Check records from a blood donation center if you have donated before
Look for blood type information in prenatal, maternity, or newborn records
Review any old lab reports or hospital discharge papers
Use a blood type listed on an organ donor card or personal medical ID if available
If none of these records exist, you cannot know your blood type reliably without testing