A study was made of 170 patients with renal pelvis or ureteric tumours, 160 of whom underwent surgery between 1948 and 1981. The most important aetiological factor was chronic phenacetin abuse: 21.7% of 83 patients with renal pelvis tumours and 11.4% of those with ureteric tumours gave a history of phenacetin abuse. The latency periods ranged from 24 to 26 years. This is the first report of a relationship between abuse of analgesics and urothelial tumours from the Federal Republic of Germany.