Colonic epithelial cell division, cell migration, and cell transit were investigated in dogs given 300 micrograms.kg-1.day-1 of the prostaglandin E1 analogue, misoprostol, for 11 weeks. The animals were then injected with [3H]thymidine and killed at timed intervals. The distribution of labeled and mitotic cells within the crypts was determined by scoring autoradiographs. There were no significant differences in mitotic index or labeling index between the two groups. The data were pooled and converted to give crypt cell production rates of 51.1 +/- 11.1 (control) and 58.24 +/- 8.6 cells per crypt per hour (test). However, the crypt length and cell population were slightly, but significantly, greater in the misoprostol-treated group (P less than 0.01). The movement of the wave of labeled cells with time after injection was used to calculate the median cell migration rates, which were 23.50 +/- 3.03 cell positions per day (control) and 18.30 +/- 2.56 (test). Thus, misoprostol had no significant effect on either the cell migration rate or the transit rates.