In Medellín, Colombia, homicides have been the leading cause of death since 1986. Their proportion among total deaths increased from 3.5% in 1976 to 42% in 1991 and subsequently decreased to 7% in 2006. From 1979 to 2008, there were 81,166 homicides (annual mean, 2,706). The homicide rates per 100,000 inhabitants were 44 in 1979 and 47 in 2008, with a peak of 388 in 1991. The current article analyzes homicides in 30 years (1979-2008) using a random sample of 3,414 forensic autopsy reports. The vast majority of victims were males, 92.8% (95%CI: 91.8%; 93.6%), mostly low-income young people from 27 to 33 years of age. Most homicides involved revenge, fights, or armed robberies. The study showed different periods in the homicide epidemic: the first 15 years, with a rapid increase, the second, with a steady decline until 1998, and the third, with a fluctuating but overall steep decline in the last 10 years. This long-term study on violence in Medellin opens possibilities for analyzing and identifying more consistent policies for intervention.