Antitrypsin activity was measured in 50 healthy controls and 100 cases of Indian Childhood Cirrhosis (ICC). The incidence of alpha-I anti-trypsin (Alpha I-AT) enzyme deficiency was strinkingly higher in cases of cirrhosis (39.0%) than in healthy controls (4%). The enzyme deficiency was more prevalent in severe grades of cirrhosis (51.5%) as compared to mild (17.6%) and moderate cirrhosis (38%). Liver function tests were severely deranged in enzyme deficient cirrhotics and the damage to the liver was directly proportional to the extent of the enzyme deficiency. The incidence of the family history of ICC was noted significantly higher in enzyme deficient cases (20%) as compared to non-deficient cases (3.3%). The enzyme deficiency was also measured in 160 first blood relatives of the deficient cirrhotics and was found to be deficient in 19.4% subjects. It is probable that the deficiency runs in families with an autosomal recessive mode of inheritance.