We compared the mortality rate of sumo wrestlers with that of the contemporaneous Japanese male population, and inferred the usefulness of an index for predicting longevity in sumo wrestlers. The standardized mortality ratios (SMR) for sumo wrestlers were very high in each period, and also high for ages from 35 to 74. Cox's proportional hazards model analysis revealed that the variables in "nyuumaku" entry year and BMI were statistically significant (p < 0.05) factors in mortality. In the survival curves, the lower BMI group had good life expectancy compared with the higher BMI group. In conclusion, the higher rate of mortality in sumo wrestlers seems to be due to the markedly higher rate of mortality from 35 to 74 years old. In sumo wrestlers, also, this study provides evidence that the higher overweight groups have substantially higher risks for mortality.