In the United States, questions about sexual activity related to eligibility for blood donation are currently
based on specific behaviors, not on sexual orientation (this includes transgender individuals).
Men who have sex with men (MSM) must wait one year after having sexual contact with another male.
Prostitutes: An individual who has engaged in sex for money or drugs since 1977 is ineligible to donate.
Other: Anyone who has had sexual contact with someone in the following categories should defer donation for 12 months since sexual contact:
1) an individual in either of the above categories (i.e., MSM or prostitute as defined above),
2) an individual with hepatitis (B or C), or
3) an individual who has ever used needles to take any drugs, steroids, or anything not prescribed by a doctor (i.e., IV drug user).
More information available at
American Red Cross Criteria for Blood Donation
Note: There are other organizations that deal with blood donations. Individual organizations have their own questionnaires and eligibility criteria that vary slightly. I've tried to use best practices information above, not American Red Cross guidance.