Historically, women who have sex with women (WSW) have been thought to be at low risk for acquiring sexually transmitted infections (STI), presumably due to the absence of genital mucosal contact present during vaginal-penile sex or due to the assumption that the vaginal mucosa experiences a lesser degree of trauma during female sex than during heterosexual sex. This assumption has been challenged and debated over the past two decades. In addition, the sexual health risks of WSW are only beginning to be understood.