A retrospective cohort study was carried out in a cardboard factory in Germany to investigate the association between exposure to trichloroethene (TRI) and renal cell cancer. The study group consisted of 169 men who had been exposed to TRI for at least 1 year between 1956 and 1975. The average observation period was 34 years. By the closing day of the study (December 31, 1992) 50 members of the cohort had died, 16 from malignant neoplasms. In 2 out of these 16 cases, kidney cancer was the cause of death, which leads to a standard mortality ratio of 3.28 compared with the local population. Five workers had been diagnosed with kidney cancer: four with renal cell cancers and one with a urothelial cancer of the renal pelvis. The standardized incidence ratio compared with the data of the Danish cancer registry was 7.97 (95% CI: 2.59-18.59). After the end of the observation period, two additional kidney tumors (one renal cell and one urothelial cancer) were diagnosed in the study group. The control group consisted of 190 unexposed workers in the same plant. By the closing day of the study 52 members of this cohort had died, 16 from malignant neoplasms, but none from kidney cancer. No case of kidney cancer was diagnosed in the control group. The direct comparison of the incidence on renal cell cancer shows a statistically significant increased risk in the cohort of exposed workers. Hence, in all types of analysis the incidence of kidney cancer is statistically elevated among workers exposed to TRI.(ABSTRACT TRUNCATED AT 250 WORDS)