The clinical efficacy and side effects of high-dose CBDCA therapy were studied in 35 cases of inoperable non-small cell lung cancer. A positive effect was obtained in about 30% of the subjects, all of who were squamous cell carcinoma patients. Incidence of clinical side effects was very low, thrombocytopenia being the major hematologic side effect. AUC, calculated from periodic measurements of free-Pt concentration in 19 subjects, was sensitive renal function, having a positive correlation with Cmax and a negative correlation with platelet nadir levels. This finding suggested the importance of establishing optimum dose levels with regard to pharmacokinetics. Patients in whom bone marrow suppression did not hamper continued therapy were treated as outpatients, many of whom retained sufficient QOL while undergoing outpatient therapy. Considering the present status of chemotherapy for NSCLC, characterized by the lack of long-term clinical efficacy and the presence of severe side effects, the present therapy is of great importance, since it can be continued with constant efficacy rates while maintaining good PS.