Over a 6-week period, 35 (41%) of 86 infants admitted with diarrhea and dehydration were found to have human rotavirus (HRV) gastroenteritis, using the Rotazyme (RTZ) test. Serum transaminase levels were measured on 44 infants on admission and 72 infants during the first 3 days of hospitalization. On admission, RTZ-positive (RTZ+) infants had higher mean and median alanine aminotransferase (ALT) levels [mean 87.5 U/L in RTZ+ vs. 50.0 U/L in RTZ-negative (RTZ-), p = 0.001; medium 60 U/L in RTZ+ vs. 41 U/L in RTZ- infants, p = 0.002], and higher mean and median aspartate aminotransferase (AST) levels (mean 64.3 U/L in RTZ+ vs. 44.0 U/L in RTZ- infants, p = 0.008; median 67.5 U/L vs. 42.0 U/L, respectively, p = less than 0.05). On admission, 72% of RTZ+ vs. 19% of RTZ- infants had ALT levels greater than 50 U/L (p = 0.0004). Maximum ALT levels from the first 3 days were also higher in the RTZ+ group (67.7% of RTZ+ vs. 34.1% of RTZ- having levels greater than 50 U/L, p = 0.005). Transaminase elevations did not correlate with dehydration of any electrolyte abnormalities. These findings suggest that transaminase elevations are common in infants hospitalized with HRV enteritis.