We analyzed longitudinal data on the cancer mortality rate in chronic dialysis patients and in the general population in Okinawa, Japan. In the general population from 1980 to 1990, the mortality rate has been stable at approximately 1.300 males and 0.897 females per thousand persons year, the male to female ratio being 1.45. In the period from 1971 to 1990, we found 91 (4.6%) patients with cancer in a group of 1,982 (824 females and 1,158 males) chronic dialysis patients; forty-nine of the 91 patient (53.8%) died by April 1, 1991. Using the standard mortality rate in the general population, which was obtained for each sex and age class (0 to 34 years, 35 to 44 years, 45 to 54 years, 55 to 64 years, and > or = 65 years), we calculated the relative risk of death from cancer in dialysis patients. The risk ratio in dialysis patients was significantly increased, being 2.48 (P < 0.05) for males and 3.99 (P < 0.05) for females. The mean (+/- SEM) age at the time of death from cancer in the dialysis group was 60.1 +/- 2.0 years in the males and 60.1 +/- 2.1 years in the females; the males were 6.3 years younger than the general population and the females were 9.3 years younger. The proportion of patients with colon cancer (both sexes) and cancer of the uterus and breast (females) was higher in the dialysis patients than in the general population.