Biopsy specimens of the gastroenterostomal area in 60 long-standing asymptomatic postgastrectomy patients and of the mid-corpus region in five normal controls were cultured in [3H]-TdR. Using radioautography, thymidine incorporation rate (TIR) and cell position of the labelled cells were scored. In the normal gastric mucosa cell proliferation was limited to the progenitor cell region. TIR of the stomal area was higher compared to the normal mucosa. In addition, an upward shift of the proliferative compartment towards the luminal surface was observed. In severe dysplasia an expanded pool of DNA-synthesizing cells was present in the uppermost layers of the gastric mucosa, but even in the surrounding non-dysplastic mucosa an upward shift of labelled cells could be demonstrated. These proliferative changes are considered to be compatible with increased cancer risk. The sequence of proliferative events suggests that early cancer formation in the gastric remnant takes place in the superficial mucosa and therefore is easily amenable to endoscopic biopsy.