A cluster of cancers at one plant in a pharmaceutical company in Sweden was the initiator for this work, which describes the cancer incidence among the laboratory and production workers at this company.The investigation is a retrospective cohort study. All employees with possible exposure to chemical, pharmacological, or biological agents and employment for at least six months at the company during 1960-1990 were included. Standardized incidence ratios (SIR) were calculated with the local county population as reference.The total cancer incidence was close to the expected. In a subcohort consisting of the highest exposed employees, an SIR of 3.5 [95% confidence interval (95% CI) 1.5-6.8] was found for urothelial tumors, while there were no urothelial tumors among the workers with the lowest exposure. An evaluation of the exposures among the subjects with urothelial tumors revealed no association with specific exposures in the workplaces. There was also a statistically significant increase in the risk for acute leukemia (SIR 4.5, 95% CI 1.2-12 ). With a 10-year induction-latency period in the calculations, the elevated risk was smaller and not significant. Although the numbers were small, there were also statistically significant overrisks for cancer of the peritoneum, the lip, and the pleura.A significant increase in the risk for urothelial tumors was found among pharmaceutical workers. All but one of those with urothelial tumors were smokers, but confounding from smoking could probably not explain the risk increase.