Applying a log-linear model, we analyzed stomach cancer mortalities during 1973-90 for 47 prefectures in Japan. The model we dealt with is based on a poisson distribution in which the expected number of deaths from stomach cancer is expressed as nrij exp(μr+αi+τrj), for ith age group and jth calendar year, for prefecture c; here nrij denotes the population size of (i, j) category in region r. Risk of stomach cance mortality decreases almost exponentially in prefectures in this period for both sexes; the decreasing rate in female is larger than that in male for all prefectures. High correlation between risk of stomach cancer mortality in male and that in female exists. Two geographical clusters of high risk for stomach cancer mortality exist; the one of them is west side of Touhoku area, and the other is southwest part of Kinki area. There is a trend such that the risk decreases more rapidly in the area of higher risk especially for male.