A pilot study was conducted to assess the efficacy and feasibility of daily low-dose cisplatin with concurrent thoracic irradiation for clinically unresectable non-small-cell lung cancer (NSCLC). Patients with inoperable NSCLC who had poor risk factors such as advanced age, poor performance status, poor lung function, or concomitant active malignancy were entered into the study. Low-dose cisplatin (6 mg/m2) was administered daily before concurrent thoracic irradiation (2 Gy/day; total dose of 60 Gy) was given. Twenty-five patients were registered. The majority of the patients had either stage IIIA (24.0%) or stage IIIB (60.0%) disease. Fifteen patients (60.0%) completed the planned treatment. Both chemotherapy and radiotherapy were stopped in 3 patients (12.0%) due to poor response, and 7 patients (28.0%) partly received radiotherapy alone as a result of their toxicity response. The proportion of total administered dose to planned dose was 90.9% for chemotherapy and 99.3% for radiotherapy, which were comparable to those in previous studies for LA-NSCLC patients without poor risk factors. Grade 3 leukopenia and neutropenia developed in 14 patients (56.0%) and 10 patients (40.0%), respectively, but grade 4 toxicity was not encountered. Grade 3 pneumonitis and esophagitis were observed in 4 patients (16.0%) and 2 patients (8.0%), respectively. The overall response rate was 60.0%. The median survival time was 22 months, and the 2-year survival rate was 50.3%. Daily low-dose cisplatin and concurrent thoracic irradiation were well tolerated even by poor-risk patients with NSCLC, and showed a therapeutic efficacy similar to that for good-risk patients.