In a case-control study of 36 men with cancer of the ureter and 307 male controls with the same age distribution tobacco smoking conferred a relative risk for this cancer of 2.9, whereas consumption of analgesics of any kind did not increase the risk. The relative risk for cancer of the renal pelvis, determined for 29 men, was 2.4 for tobacco and 6.0 for phenacetin-containing analgesics. Analgesics containing no phenacetin conferred no increased risk for cancer at this site. Data for 13 women with ureteral cancer, 5 of whom had taken phenacetin, are presented but not analyzed.