The mortality among 3572 white male pulp and paper mill workers employed for at least 1 year between 1945 and 1955 at one of 37 pulp and paper mills in Washington, Oregon, or California was studied. The overall mortality was significantly lower than expected. There were nonsignificant excesses in mortality due to five site specific malignancies, stomach cancer, prostate cancer, kidney cancer, bladder cancer, and lymphatic cancer. The excess of deaths due to lymphatic cancer and stomach cancer corroborated reports based on state vital statistics and preliminary studies of pulp and paper mill workers. Process specific standardized mortality ratios, which were highest after 20 years since first employment in the mills, were detected for lymphatic cancer and stomach cancer. The excess of lymphatic cancer was restricted to workers employed in sulfate mills, and the stomach cancer excess was limited to workers in sulfite mills. The authors indicate that there is a need for further research to distinguish etiologic agents involved in the development of these cancers among paper and pulp mill workers.