To evaluate the relationship of selected medical conditions and medications with cancers of the renal pelvis and ureter, we interviewed 308 subjects with renal pelvis cancer, 194 subjects with ureter cancer and 496 control subjects in 3 areas of the United States. After controlling for the effects of smoking, age, gender and geographic residence, a history of hypertension (reported to have been diagnosed more than 5 years before interview) was associated with a small but significantly increased risk (odds ratio [OR] = 1.3; 95% confidence interval [CI], 1.0-1.8), whereas no relationship was observed with a variety of other medical conditions or medications. Stratified analysis showed that the risk associated with hypertension was twice as high among users of diuretics or other antihypertensive drugs (OR = 2.4; 95% CI, 1.1-4.9) as it was among those who never used these medications (OR = 1.2; 95% CI, 0.8-1.7). Our findings suggest that the association previously reported between hypertension and renal cell cancer may extend to cancers of the renal pelvis and ureter.