The drug sensitivity test using a human tumor clonogenic assay is an in vitro technique providing a high degree of accuracy for predicting the clinical response to anticancer drugs. The author applied this assay to compare the in vitro anticancer efffects of four anthracycline-anthraquinone analogues against lung cancer. The drugs tested in the present study were adriamycin(ADM), aclarubicin(ACR), THP-adriamycin(THP-ADM) and mitoxantrone(MIT). A tumor was defined as sensitive, when the suviving fraction of colony-forming units was reduced 70% or more at a clinically achievable plasma concentration of these drugs in man. Tumor specimens from 100 individual patients were placed in culture. Forty-five specimens (45%) formed enough colonies to test durg sensitivity. Fourteen of the 31 specimens(45%) tested were found to be sensitive fof ACR, 15 of 35(43%) for THP-ADM, 10 of 30(33%) for MIT, and 7 of 43(16%) for ADM. These fingings indicated that the activity of ACR and THP-ADM is stronger than that of ADM in the treatment of lung cancer.