In this study, the authors estimated overall and cause-specific mortality among prostitute women. They recorded information on prostitute women identified by police and health department surveillance in Colorado Springs, Colorado, from 1967 to 1999. The authors assessed cause-specific mortality in this open cohort of 1,969 women using the Social Security Death Index and the National Death Index, augmented by individual investigations. They identified 117 definite or probable deaths and had sufficient information on 100 to calculate a crude mortality rate (CMR) of 391 per 100,000 (95% confidence interval (CI): 314, 471). In comparison with the general population, the standardized mortality ratio (SMR), adjusted for age and race, was 1.9 (95% CI: 1.5, 2.3). For the period of presumed active prostitution only, the CMR was 459 per 100,000 (95% CI: 246, 695) and the SMR was 5.9 (95% CI: 3.2, 9.0). Violence and drug use were the predominant causes of death, both during periods of prostitution and during the whole observation period. The CMR for death by homicide among active prostitutes was 229 per 100,000 (95% CI: 79, 378), and the SMR was 17.7 (95% CI: 6.2, 29.3). Deaths from acquired immunodeficiency syndrome occurred exclusively among prostitutes who admitted to injecting drug use or were inferred to have a history of it.