We reviewed 41 cases of transitional cell carcinoma of the renal pelvis and ureter with special reference to the coexistence or subsequent development of bladder cancer. Bladder cancer was associated with an upper urinary tract neoplasm in 20 of the 41 cases (48 per cent). Most of these patients (15 of 20) were treated by radical total cystectomy of 1-stage nephroureterocystectomy. The incidence of ureteral stump cancer after nephrectomy alone or incomplete nephroureterectomy was 64 per cent (7 of 11 patients). Twelve surgically removed specimens of the renal pelvis, ureter and/or bladder were examined extensively for the histological association of pre-neoplastic disease, such as atypical hyperplasia and carcinoma in situ. Every specimen had these changes of the urothelium adjacent to and remote from obvious tumors.