We measured serum GOT levels in babies with atopic dermatitis and food allergy. Two hundred and fourteen babies (133 male, 18 female, under 2 years of age) who first visited the Department of Allergy in the National Children's Hospital were examined. Their serum GOT levels were higher than normal; the younger they were, the higher the serum GOT levels were. We carried out the 13-methacetin breath test (MBT) on 11 babies with atopic dermatitis and high serum GOT levels as well as 5 normal babies to estimate their hepatic microsomal function. 13C-methacetin was administered (0.5 mg/kg) orally, and breath was collected at 30 minutes before and immediately before administration. After administration it was collected at 15 minute intervals for the first hour and 45 minute intervals for 90 consecutive minutes afterwards. The level of 13CO2 in their breath was determined with a mass spectrometer. The peak level of 13CO2 excretion (%dose/hr) in the atopic babies with high serum GOT levels was lower and the time required for 13CO2 excretion to reach its maximum level was longer than in normal babies. Also their 13CO2 clearance rate (%/hr) was lower. These results suggested that there was some relationship between atopic dermatitis and liver dysfunction in babies.