Twenty-one patients experienced headache related to sexual activity. Two varieties of headache could be distinguished from the clinical histories. The first, developing as sexual excitement mount, had the characteristics of muscle contraction headache. The second, severe, throbbing or 'explosive' in character, occurring at the time of orgasm, was presumably of vascular origin associated with a hyperdynamic circulatory state. Two of the patients with the latter type of headache had each experienced episodes of cerebral vascular insufficiency on one occasion which subsequently resolved. A third patient in this category had a past history of drop attacks. No evidence of any structural lesion was obtained on clinical examination or investigation, including cerebral angiography in seven patients. Eighteen patients have been followed up for periods of two to seven years without any serious intracranial disorder becoming apparent. While the possibility of intracranial vascular or other lesions must always be borne in mind, there appears to be a syndrome of headache associated with sexual excitement where no organic change can be demonstrated, analogous to benign cough headache and benign exertional headache.