Thirty-four randomized, partially gastrectomized subjects (12 with a Billroth II, 11 with a Billroth I, and 11 with a total biliary diversion reconstruction) were studied in order to assess the relationships between bile reflux, gastric histology, and cell proliferation kinetics. Bile acid quantity and concentration in the gastric aspirates progressively decreased from Billroth II to Billroth I to total biliary diversion (after which reflux was almost absent). Perianastomotic mucosa in Billroth II subjects showed the greatest degree of foveolar hyperplasia, and this decreased markedly with increasing distance from the anastomosis. Hyperplastic changes were less evident in Billroth I, and virtually absent in total biliary diversion subjects. The overall foveolar hyperplasia-like behavior of cell kinetic parameters (total pit cell number, labeled pit cell number, and labeling index) was shown. Moreover, subjects with mean bile acid concentration greater than 150 mumol/L had both a greater prevalence of foveolar hyperplasia and greater values of cell kinetic parameters than those with mean bile acid concentration less than or equal to 150 mumol/L. A superficialization of the proliferative compartment was also evident in the former group. These results show a close relationship between postgastrectomy bile reflux, foveolar hyperplasia, and cell kinetic parameters. Histologic and cell kinetic findings are probably the expression of gastric adaptation to chronic bile reflux exposure. Moreover, the type and entity of cell kinetic involvement and its relationship to foveolar hyperplasia and reflux may suggest new "tools" in post-gastrectomy surveillance and help to clarify patterns of gastric carcinogenesis.