The rate of cell migration in the small intestine during enteric viral infections has not been assessed previously. CD-1 mice (33 days old) were infected perorally with 1.0 X 10(8) plague-forming units of coxsackievirus B5 and 12 hr later were injected intraperitoneally with 2 micron Ci of [3H]thymidine/g of body weight. After 2, 12, 24, 48, 60, and 72 hr, mice were killed, and the small intestine was removed. Specimens obtained at each interval were examined by radioautography; similar specimens were titrated for virus by plaque assay in HeLa cells. In mice perorally infected with coxsackievirus B5, epithelial cells migrated from crypt to villus tip in 60 hr, as compared with 48 hr in uninfected control mice and 24 hr previously reported for mice perorally infected with enteric bacteria (e.g., Salmonella typhimurium). Virus was recovered from intestinal tissue, but no inflammatory response in the limina propria was apparent. These observations are consistent with previous report that substrate absorption rates may be altered during viral and bacterial enteric infection.