Vulvovaginal reactions to seminal fluid occurred in all four women in a family. The reactions consisted of stinging, burning, and pain in the vagina, starting during coitus or immediately after ejaculation, and persisting for 2 to 72 hours. The vagina and vulva were red and swollen, with urticaria on the labia. Although skin tests showed a positive reaction in two of three women tested, no sperm agglutination antibody was detected. Benadryl was effective in preventing the development of vulvovaginal reactions completely in one woman and partially in two others.