<b>OBJECTIVEb>The aim of this survey was to compare the seroprevalences ofHelicobacter Pylori (H. pylori) and chronic atrophic gastritis (CAG) in Tanzania and the Dominican Republic, both of which are tropical countries, and thereafter compare the prevalences in Tanzania and the Dominican Republic with prevalences from our previous studies done in Japan (1991) and China (1996/97).

<b>METHODSb>Community-based study in which 573 inhabitants of Tanzania and 1,215 inhabitants of the Dominican Republic answered detailed questionnaires on upper digestive tract diseases, and then underwent screening for gastric cancer by serum pepsinogen and testing for antibody toH. pylori.

<b>RESULTSb>After adjusting to the 'Age-Standardized Rate' (ASR) using the world population in 1995, the seroprevalences ofH. pylori infection in male and female subjects for Tanzania (m=85.3% & f=88.2%) were very high compared to those for the Dominican Republic (m=63.5% & f=62.4%) and Japan (m=62.0% & f=46.8%), and similar to those of China (m=78.0% & f=77.3%). Also, the agestandardized prevalences of CAG in males and females for Tanzania (m-0.237& f=0.458). were higher than those of the Dominican Republic (m=0.168 & f=0.211) and China (m=0.111 & f=0.107) and compared well with those of Japan (m=0.266 & f=0.352).

<b>CONCLUSIONSb>Although Tanzania and the Dominican Republic are both developing countries, Tanzania had a very high age-standardized prevalence ofH. pylori and CAG compared to that of the Dominican Republic, which showed a trend similar to that of Japan.