Men who have sex with men with regard to trans women, people born either biologically male or with ambiguous genitalia who self-identify as female. Some sources consider trans women who have sex with men to be MSM, others consider women who are trans "alongside" MSM, and others are internally inconsistent (defining transgender women to be MSM in one place but referring to "MSM and transgender" in another). Determining the number of men who have ever had sex with another man is difficult. Worldwide, at least 3% of men, and perhaps as high as 16% of men, have had sex at least once with a man. These
Men who have sex with men Men who have sex with men Men who have sex with men (MSM), also known as males who have sex with males, are male persons who engage in sexual activity with members of the same sex, regardless of how they identify themselves; many such men do not sexually identify as gay, homosexual or bisexual. The term "MSM" was created in the 1990s by epidemiologists to study the spread of disease among men who have sex with men, regardless of identity. The term "MSM" is often used in medical literature and social research to describe such men as a group for