Intensity of photophobia in dull and bright light was assessed in 39 migrainous patients and 15tension headache sufferers during headache, and in 20 nonheadache control subjects. In 24 patients,measurements were repeated during the headache-free interval. Subjective estimates of glare andlight-induced pain were greatest in patients with migraine at the time of examination, but ratings bytension headache sufferers also exceeded control ratings at most levels of illumination. In 19 of 25patients with unilateral headache, light-induced pain was greater on the symptomatic side. During theheadache-free interval, glare ratings in dull and bright light, and pain ratings in bright light, weregreater in headache-prone patients than in nonheadache controls. Sensitivity to glare could thusform part of a general hyperexcitability of the special senses, while bright light appears to exacerbatepain resulting from activation of trigeminal pain pathways during headache.