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 of 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.