I f you can't quite remember what your blood type is -- don't worry. That just means you're among the 33% of Americans who ...

The results will tell you whether you have A, B, AB, or O blood and whether your Rh factor is positive or negative. Apart from your healthcare provider ordering a standard ABO blood test, you could ...

O negative is a rare blood type that can be given to anyone. It is called the “universal donor” and is very useful in ...

It's a bit simplistic, but you can think of the Rh factor as a protein that is either present (positive) or absent (negative) on red blood cells. Exact percentages vary with race, but most people ...