Certain ovarian tumors which are not usually considered to be functional have been found in the presence of virilism on estrinism. This report concerns an unusual case of huge, bilateral Krukenberg tumors associated with massive virilization occurring during pregnancy. Virilization of the female infant also occurred.A thorough endocrine investigation was performed preoperatively with subsequent postoperative follow-up. The decrease of the tremendously elevated urinary steroids to normal levels following removal of the ovarian tumors strongly suggest that the ovaries were the source of the androgenic hormones. Also the absence of all hormonal manifestations during recurrence of the tumor lends further support to this thought.Evidence is presented to show that the androgen production by the ovaries was not significant until after the first trimester of pregnancy. Histochemical studies of the ovarian tissue appear to offer convincing evidence that the ovarian stroma cells, rather than the tumor tissue itself, was the actual site of hormone production.At autopsy, no primary lesion of the gastrointestinal tract was found. It is postulated that the primary site of the tumor was in the breast.A review of the previously reported cases of Krukenberg tumors associated with virilization is presented.