The authors conducted a case-control, interview-based study of the risk of developing cancer from asbestos in drinking water. The Everett, Washington, area was selected for the study because of the unusually high concentration of chrysotile asbestos in the drinking water it draws from the Sultan River. Through a population-based tumor registry, the authors identified 382 individuals with cancer of the buccal cavity, pharynx, respiratory system, digestive system, bladder, or kidney, diagnosed between 1977 and 1980, and then interviewed them or their next-of-kin. The authors conducted similar interviews of a control group of 462 individuals. Finally, interviews were validated in several ways, including comparing the collected data with that from secondary sources. Estimates of exposure to asbestos in drinking water were based on residence and workplace history, and on individual water consumption. Four different measures of exposure were used. Cancer risk was estimated by logistic regression and other methods. The authors found no convincing evidence for cancer risk from imbibed asbestos.