Renal cell carcinoma has been linked to hypertension and antihypertensive medications. We investigated the association between renal cell carcinoma and the use of thiazide in a case-control study of 167 men and 90 women. Subjects were members of the Kaiser Permanente Medical Care Program in northern California (United States) who had taken a multiphasic health check-up from 1964 through 1988 and who were evaluated for cancer until the end of 1989. Control subjects received the same check-up, were matched by gender, year of check-up, and age at check-up, and had to be in the health plan until the date on which renal cell carcinoma was diagnosed. Data on known and potential risk factors, including hypertension, body mass index (BMI), and smoking status, were collected from the record of the check-up. Thiazide use was abstracted from the medical chart, which was reviewed from the date of the first entry until the date on which the cancer was diagnosed or the equivalent date for control subjects. The mean follow-back to check-up was 11.3 years. Among women, we found a significantly elevated risk of 4.0 (95 percent confidence interval [CI] 1.5-10.8) associated with ever having used thiazide after we adjusted for smoking, BMI, hypertension, and history of kidney infection at check-up. We did not find a statistically significantly elevated risk in men. Smoking was related to renal cell carcinoma in men (odds ratio [OR] 2.5, CI = 1.1-5.4) for those who smoked at least one pack per day compared with those who had never smoked, but was not related in women.(ABSTRACT TRUNCATED AT 250 WORDS)