Of the 28,857 cancer cases registered by the Finnish Cancer Registry in 1955, 1960 and 1965, 63 patients had committed suicide by the end of 1970. The suicide rate among males was 1.3 times higher (p less than 0.01) and among females 1.9 times higher (p less than 0.05) than the rate in the general population. The highest suicide risk (relative risk 2.5, p less than 0.001) was associated with gastrointestinal cancer. Patients with a non-localized tumor at diagnosis had a two-fold risk of suicide and the rate was higher among patients undergoing no treatment, or treatment with chemotherapy or hormones only. It was estimated that 23% of all suicides among male cancer patients and 46% among female cancer patients was associated with the patients having cancer.