In order to evaluate usefulness of the peripheral lymphocyte culture method, challenge test, macrophage migration inhibition test for the diagnosis of drug induced liver injury. The present studies were carried out on 28cases of drug induced liver injury diagnosed by clinical symptoms and signs, and histological change. The positive results were found in 7 of 8cases (88%) in the challenge test, in 13 of 26cases (46%) in the peripheral lymphocyte culture method, and in 4 of 7cases (57%) in macrophage migration inhibition test. The challenge test showed the highest positive rate, being administered the dose for one time or a day of the suspected drug when clinical symptoms and signs recovered completely. The lymphocyte stimulation test was positive in 8 of 10cases which showed over 50 units of icterus index and in 5 of 6cases which showed over 15 units of serum alkaline phosphatase activity (Bessey-Lowrey) during the course. The macrophage migration inhibition test was positive in 3 of 4cases which showed over 50 units of icterus index and in all of 3cases which showed 10 units of serum alkaline phosphatase activity during the course. It was also demonstrated that lymphocyte culture method and macrophage migration inhibition test are rather more useful than challenge test for the diagnosis of the case with subacute hepatitis or fluminant hepatitis.