National trends in death certification rates from cancer of the stomach in Italy over the period 1955 to 1979 were analyzed using a standard cross-sectional approach and a log-linear Poisson model to isolate the effects of birth cohort, calendar period, and age. Overall, age-standardized death certification rates decreased from 47.04 to 30.74/100,000 males (average annual rate of change, assuming that the decrease has been constant, -1.8%) and from 34.55 to 19.27/100,000 females (average annual rate of change -2.4%). The decreases were even larger in middle age for both sexes. Both cohort and period of death curves were markedly downwards. However, cohort values did not decrease for generations born around the second world war (1935-1945), thus indirectly confirming the importance of (dietary) habits in childhood on subsequent gastric cancer risk. Further, the geographic distribution of certified mortality from gastric cancer in the 95 Italian provinces over the period 1975 to 1977 was analyzed. Death certification rates were about 10% lower for both sexes in the 14 provinces including the largest urban concentrations (over 250,000 inhabitants) than in the remaining areas. This finding might be related to earlier availability of modern food processing and storage in urban areas. It is, however, more difficult to explain the lower mortality rates (about 50% in both sexes) in the southern compared with the central and northern areas, since southern Italy is the less developed part of the country. Likewise, there appears to be at present little satisfactory explanation for the several clusters of exceedingly high mortality areas scattered in northern and central Italy, since some of these areas are several hundred kilometers apart, and there is no obvious common denominator in diet or other environmental factors that may explain their higher gastric cancer mortality rates.