The risk of suicide or other violent death was assessed among 296,331 patients with cancer in Denmark from 1971 to 1986 by linkage between the National Cancer Registry and mortality files. There were 1,637 violent deaths, of which 568 were suicides. The relative risk (RR) of suicide was significantly increased in the first 2 years after a cancer diagnosis, independent of age at cancer diagnosis. A lower suicide risk was seen after diagnosis of localized cancer (RR = 1.3; 95% confidence intervals [CI]: 1.1 to 1.4), compared with that seen after a nonlocalized cancer (RR = 1.9; 95% CI: 1.5 to 2.4). High risks for suicide were observed for patients of each sex after diagnoses of tumors of the brain and nervous system and with cancer of the lung, stomach, rectum, and kidney; high risks were found among male patients only after a diagnosis of lymphoma or pancreatic cancer. Surprisingly, the risk of suicide has increased significantly in more recent years.