Suicide rates are higher at high altitudes; some hypothesize that hypoxia is the cause. We examined 8,871 suicides recorded in 2006 in 15 states by the National Violent Death Reporting System, with the victim's home county altitude determined from the National Elevation Dataset through FIPS code matching. We grouped cases by altitude (low less than 1000 m; middle = 1000-1999 m; high greater than or equal to 2000 m). Of reported suicides, 5% were at high and 83% at low altitude, but unadjusted suicide rates per 100,000 population were higher at high (17.7) than at low (5.7) altitude. High and low altitude victims differed with respect to race, ethnicity, rural residence, intoxication, depressed mood preceding the suicide, firearm use and recent financial, job, legal, or interpersonal problems. Even after multivariate adjustment, there were significant differences in personal, mental health, and suicide characteristics among altitude groups. Compared to low altitude victims, high altitude victims had higher odds of having family or friends report of a depressed mood preceding the suicide (OR 1.78; 95%CI:1.46-2.17) and having a crisis within 2 weeks before death (OR 2.00; 95%CI:1.63-1.46). Suicide victims at high and low altitudes differ significantly by multiple demographic, psychiatric, and suicide characteristics; these factors, rather than hypoxia or altitude itself, may explain increased suicide rates at high altitude.