A case of maple syrup urine disease was reported. This female infant was hospitalized at the 15th day after birth, abecause of poor sucking and fever. Two weeks after hospitalization peculiar odor of maple syrup in the urine was detectected and 2, 4dinitrophenylhydrazine reaction of the urine became positive. At 31/2 months of age treatment wa s begun by the diet without valine, leucine and isoleucine. But she died of pneumonia at the age of 41/2months.