In order to study the frequency and characteristics of post-angiography headache, we interviewed 45 consecutive patients (mean age +/- SD = 57 +/- 15 years; M/F = 15/30) who underwent transfemoral cerebral angiography for: ischemic cerebrovascular disease (n = 33); suspected arteriovenous malformations (n = 4; one confirmed); suspected cerebral aneurysm (n = 5; two confirmed); and arterial dissection (n = 3; one confirmed and one was a follow-up study of a previously demonstrated dissection). Postangiography headache developed in 15 (33%) patients, 125 +/- 99 min after the completion of the study. It was unilateral in nine (60%) patients, homolateral to the usual side of migraine headache in two or three migraineurs, and pulsating in six (40%). Nausea, vomiting, photophobia, and phonophobia accompanied postangiography headache in 20%, 7%, 33%, and 20% respectively. Postangiography headache fulfilled the International Headache Society criteria for migraine without aura (except for the number of attacks) in 27% of patients. Patients with and those without postangiography headache were comparable in mean age, sex, and indication for angiography. Fifty-three percent (8/15) of patients with postangiography headache and 23% (7/30) of the non postangiography headache group reported prior recurrent headaches (P = 0.047, likelihood ratio chi-square). Postangiography headache has the characteristics of delayed arterial pain which may be related to a catheter-induced or contrast dye-induced release of vasoactive substances, notably nitric oxide and serotonin.