Liver dysfunction in patients with measles infection is reported commonly in European and American literatures, but those in Japan are relatively rare. We observed the abnormal elevation of serum transaminase in 17 of 18 juvenile patients with measles from December 1989 to February 1990, however severe complications such as pneumonia or meningitis were not observed. A diagnosis of measles was made by typical clinical symptoms and the elevation of IgM antibody against measles (EIA method). Ninety four percent of the patients showed the elevation of serum transaminase, (GOT 118.6 +/- 96.2 IU/l, GPT 161.5 +/- 167.6 IU/l), and all patients recovered completely in 30.5 +/- 12.8 days after the onset. The abnormal evaluation of serum LDH was seen in 94% of the patients, (mean value was 872.2 +/- 216.2 IU/l). LDH4 mainly elevated in most cases, however, LDH5 elevated only in 4 cases. The intensity of liver dysfunction did not correlate to the severity of measles in the present cases. It is considered to be characteristic to the patients with measles that the serum level of LDH is markedly high as compared with that of transaminase.