Forty-three persons with cancer of the renal pelvis or ureter were compared with 509 persons with cancer of the bladder and with controls. Controls were drawn from the population in which the cases occurred. Data were gathered by at-home interviews. Cancers of all 3 sites occur predominantly in men and in old age. Some environmental exposures associated with bladder cancer, i.e., cigarette smoking, coffee drinking, and work with leather, are also related to cancer of the renal pelvis and ureter. However, it appears that only high levels of exposure are associated with increased risk of cancer of the renal pelvis and the ureter. Nonetheless, if causal, these associations would account for most cancers at these sites. The rapid transit of carcinogens through the renal pelvis and ureter may explain the association of cancer at these sites with only high-level exposures.