Fourteen women taking oral contraceptives were admitted during a five-year period because of acute cerebrovascular lesions. A diagnosis of major cerebral embolism was established in four of them. No source of embolism was found, and thorough investigation failed to reveal any predisposing illness. Cerebral embolism was a probable diagnosis in several of the remaining 10 patients. A comparison was made with the strokes occurring in women not taking contraceptive pills in corresponding age groups.