What records are available that might contain someone’s blood type?

Blood types can be helpful in determining paternity or non-paternity. Obviously, we would prefer to use DNA tests, but for people who have passed away without being DNA-tested, and especially if they had no (known) children, then blood types could be useful. Blood types cannot prove paternity, but they can disprove paternity. For example, a type-O mother cannot have a type-A child with a type-O father or with a type-B father. The father must be someone with blood type A or type AB.

Blood typing was invented in the early 20th century and was used on a limited basis in WW I and probably wasn’t widely used until the 1930s or 1940s, so it would obviously never be available before that time period.

The records I know of that might have blood type are dog tags and driver’s licenses.

I also imagine that blood type might be on some birth certificates. That won’t help in my research since birth certificates in Georgia, where my family is from, are subject to privacy restrictions, The only ancestor for which you can legally request a birth certificate in Georgia is your parent.

Are there any other likely ways of determining the blood type of deceased ancestors?

  • The medical cards? Or military records? I think that in civil life before WWII blood type was not widely recognized Commented Nov 30, 2017 at 18:36
  • I just looked at a birth certificate from Florida from 1982, and there was no blood type.
    – Jamie Cox
    Commented Nov 30, 2017 at 20:48
  • I suspect that blood type would show up on the hospital's birth record, but not the state vital record.
    – cleaverkin
    Commented Dec 5, 2017 at 17:59
  • Edited to correct your statement that there are no birth certificates available in the state of Georgia. General compliance was reached around 1928, per the FamilySeach Wiki: familysearch.org/wiki/en/Georgia_Vital_Records#Birth_Records
    – Jan Murphy
    Commented Jan 1, 2018 at 19:37
  • @JanMurphy Birth certificates were recorded in Georgia, but you can't get them -- with very few exceptions. The only ancestor for which you can legally request a birth certificate in Georgia is your parent. Birth registration not beginning until 1919 is irrelevant since blood types were not used that far back anyway.
    – Jamie Cox
    Commented Jan 1, 2018 at 19:56

2 Answers 2


Blood type is found in a person's military records and their hospital records. I discovered my grandfather's blood type by requesting his military records. I found out my mother's by requesting her medical records from the hospital where I was born. If a person has given blood, their blood type is kept on file there as well. I have been unable to find blood types with any other method.

  • 2
    I wonder how long hospital records are typically kept.
    – Jamie Cox
    Commented Jan 1, 2018 at 20:02
  • 1
    The length of time hospital records are kept varies by state. Some keep for 10 years after inactivity. Others keep for 20 to 30 years after inactivity. You would need to ask the hospital directly to find out.
    – user7481
    Commented Jan 1, 2018 at 20:13

Records, fine, but remember: where there are Records (viz: human input) there can also be mistakes & errors.

When I was 18 and enlisted in the US Army, way back when Custer was still a Colonel, the Army put my blood type (which is what this conversation begins with) as A+ and it's not! It's A- it's a good thing I never had a blood transfusion whilst in Uncle Sam's Boy Scouts.

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