Prolonged elevation of the serum transaminase concentration in an asymptomatic child is usually thought to be secondary to liver disease. Four children with unexplained persistent elevation of serum transaminase concentration were referred to a pediatric gastroenterologist for studies of liver disease. Subsequent evaluation disclosed abnormal muscle biopsy findings in all four patients. This experience suggests that an appropriate workup for occult myopathy is indicated in such patients before invasive diagnostic procedures for evaluation of liver disease are undertaken.