The risk of cancer among firefighters, who are potentially exposed to known and suspected carcinogens, e.g., fire combustion products, vehicle emissions, and shift work, was studied. Using data from the Nordic Occupational Cancer study, 2470 cancer cases were observed in the follow-up up to 2005 out of the 16,223 men studied. Excesses of non-melanoma skin cancer, lung adenocarcinoma, malignant melanoma, colon cancer, prostate cancer, and mesothelioma were observed. Risks of mesothelioma, lung adenocarcinoma, and non-melanoma skin cancer were highest among firefighters over 70. SIR for prostate cancer and melanoma were highest among those under age 50.