In the epidemiological study among 379 adult men with permanent residence at 4300 meters (14,200 feet), we found 32.2% with migraine (mostly migraine with aura), 15.2% with tension-type headache (episodic more than chronic), and 7.2% with other headaches. The frequency of migraine increased with age from 30.1% in the 20–29 year age group to 36.8% in the 50–59 year group. Episodic tension-type headaches also showed this trend. We found an age-specific increase in the frequency of high hemoglobin (Hb > 213 g/l), low oxygen saturation (O2 saturation <81.5%), and high chronic mountain sickness scores. Male migraineurs and those with more than two headaches per month had the highest hemoglobin levels and chronic mountain sickness scores when compared with high altitude men without headaches. © 1994, International Headache Society. All rights reserved.