A total of 229 consecutive gastrectomy specimens (129 from patients living in Hawaii and the remaining 100 from patients living in Sweden) were examined under high-powered light microscopy to investigate the characteristics of the pyloric cells. Six phenotypes of pyloric cells were found: (1) pyloric mucus secreting low-cylindric cells with bubbly cytoplasm, (2) pyloric mucus-negative cells with small cytoplasmic vacuoles (usually subnuclear), (3) pyloric mucus-negative cells with large cytoplasmic vacuoles, (4) pyloric cells with dense eosinophilic luminal border, (5) pyloric cells with fine eosinophilic cytoplasmic granules, and (6) pyloric cells with homogeneous "glassy" cytoplasm. In addition, pyloric cells with cilia at their free border were recorded among five of the six phenotypes of pyloric cells. The data indicate that pyloric (nonciliated) cells with large cytoplastic vacuoles were more often recorded in patients living in Hawaii (27.1%) than in Sweden (1.0%). Ciliated cells were more common in patients living in Hawaii (40.3%) but less common in Scandinavians (2.0%). From the Hawaiian specimens having large vacuolated pyloric cells, 79.5% also demonstrated ciliated cells; the same phenomenon occurred in only 9.1% of the Swedish specimens. Differences in percentage of ciliated cells between Hawaiian and Swedish specimens were also recorded in four of the five pyloric cell phenotypes. The present findings suggest that local environmental factors may influence the frequency of different phenotypes of pyloric cells and their ciliated variants.