The prevalence of hypertransaminasemia and the effect of gluten-free diet (GFD) were evaluated in 158 consecutive adult celiac patients, 127 women and 31 men, aged 18 to 68 years (mean, 32). At diagnosis, 67 patients (42%) had raised aspartate and/or alanine transaminase levels (AST and ALT; mean, 47 IU/L, range, 30 to 190; and 61 IU/L, range, 25 to 470, respectively), whereas 91 patients had normal liver function tests (LFT). Patients with and without hypertransaminasemia were comparable for epidemiological data, body mass index (18.5 vs. 19.6), and severity of intestinal histological involvement. All patients were given a strict GFD and were followed for 1 to 10 years (median, 4). At 1 year, a highly significant improvement in intestinal histology was observed in both groups (P < .0001). In the 67 patients with raised transaminase levels body mass index (BMI) also increased significantly (from 18.5 to 21.0, P < .001), and transaminase levels normalized in 60 (95%). In the other seven cases liver biopsy showed fatty infiltration in two and chronic active hepatitis (CAH) in the other five, related to chronic infection with hepatitis B virus in three and hepatitis C virus in one, and to autoimmune type in the fifth. We conclude that in adult celiac patients elevated serum transaminases are a frequent finding and normalize in most cases after GFD. When they persist, liver biopsy is mandatory to further investigate hepatic involvement, which is our series was mainly attributable to CAH.