A nosocomial outbreak of hepatitis A occurred after hospitalization of a 21-month-old girl with amebic liver abscess and unsuspected, anicteric hepatitis A. The index patient, who had an acute diarrheal illness prior to enzyme elevations, seroconverted from IgM hepatitis A antibody to IgG hepatitis A antibody. Of the 103 hospital personnel with known or potential exposure, three physicians (2.9%) contracted clinical hepatitis A, 27 to 29 days after their initial contact with the source patient. A fourth physician developed subclinical infection. Two of the three clinical cases occurred in two of the three primary care physicians of the source patient. Hepatitis A should be considered in any patient with acute, unexplained liver enzyme abnormalities. Diarrhea occurring in a fecally incontinent child incubating hepatitis A may increase the risk of transmission.