Previous studies have shown that orally administered epidermal growth factor (EGF) enhances neonatal intestinal growth and that it may be absorbed in the intestine and bound by other organs. This study investigated whether the ingestion of EGF would be associated with growth of nonintestinal organs. In short-term studies, 87 newborn rat pups were fed artificial formula containing various concentrations of EGF for 39 h. In long-term studies, suckling newborn pups were fed EGF or an equal volume of distilled water for 5 days. The pups fed formula containing EGF for 39 h had a significant increase in hepatic incorporation of [3H]thymidine into DNA compared with pups not fed EGF. By 5 days of age, 13 pups fed EGF had heavier livers that contained more DNA and RNA compared with 14 control pups. Moreover, EGF-fed pups had heavier hearts and kidneys than pups fed no EGF. These data suggested that ingestion of EGF is associated with the growth of nonintestinal organs.