In 119 gastrointestinal patients, serum transaminases (ASAT) and alkalines phosphatases (AP) were prospectively measured on the first and the twenty first days of a continuous enteral nutrition (CEN) regimen. The exclusion criteria were: recent surgical procedure, transfusion or total parenteral nutrition (TPN), or a cancer during the previous five years. Of the 119 patients, 71 patients were included in the study. The patients received: (a) an exclusive elemental CEN (n = 25, all with Crohn's disease) or non elemental CEN (n = 9), providing 40 kCal/kg of ideal body weight (IBW)/day; (b) a non exclusive non elemental CEN providing a minimum of 30 kCal/kg IBW/day. Of the 56 patients having normal hepatic function tests (HFT) on the first day, only 2 developed mild abnormalities (incidence of 3.6%). Of the 15 remaining patients having abnormal HFT on the first day, HFT improved or returned to normal in 8 cases. During CEN: the appearance of abnormal HFT seems rare, pre-existing abnormalities can improve and there is no associated morbidity. These results suggest that there is no hepatic side effects of CEN, in contrast to TPN, and that CEN must be preferred over TPN whenever the choice is possible.