Police officers are exposed to occupational hazards which may put them at increased risk of cancer We examined the incidence of cancer in a cohort of 2234 white-male police officers in Buffalo, New York. The study population was followed for 31 years (1976-2006). The incidence of cancer, ascertained using a population-based tumor registry, was compared with 9 US regions using the Surveillance Epidemiology and End Results (SEER) program data. Four hundred and six officers (18.2%) developed cancer between 1976 and 2006. The risk of overall cancer among police officers was found to be similar to the general white-male population (standardized incidence ratio [SIR] = 0.94, 95%, confidence interval [CI] = 0.85-1.03). An elevated risk of Hodgkin's lymphoma was observed relative to the general population (SIR = 3.34, 95%, CI = 1.22-7.26). The risk of brain cancer, although only slightly elevated relative to the general population (SIR = 1.61, 95%, CI = 0.73-3.05), was significantly increased with 30 years or more of service (SIR = 2.92, 95%, CI = 1.07-6.36). Incidence ratios were significantly lower than expected for skin and bladder cancer Police officers were at increased risk of Hodgkin's lymphoma overall and of brain cancer after 30 years of service.