We examined the efficacy and safety of the combination of gemcitabine and nedaplatin in patients with untreated advanced non-small-cell lung cancer. Thirty-four patients (24 men and 10 women) with a mean age of 69 years (range, 39-75 years) were treated every 3 weeks with gemcitabine (1,000 mg/m(2) on days 1 and 8) and nedaplatin (100 mg/m(2) on day 1). Four patients had stage IIIB disease and 30 patients had stage IV disease. None of the 33 patients achieved a complete response, but 10 achieved a partial response, for a response rate of 30.3% (95% confidence interval, 15.6-48.7%). One patient could not be evaluated for response because only one course of chemotherapy had been administered due to grade 3 eruption. The median survival time was 9.0 months (range, 1-17 months). Grades 3-4 hematological toxicities included leukopenia in 47% of patients, neutropenia in 62%, thrombocytopenia in 56%, and anemia in 44%. Grades 3-4 nonhematological toxicities included nausea and vomiting in 6% of patients, diarrhea in 3%, and hepatic dysfunction in 9%. There were no treatment-related deaths. The dose intensities were 89.6% and 86.7%, respectively, of the planned doses of gemcitabine and nedaplatin. Our results suggest that the combination of gemcitabine and nedaplatin is an acceptable treatment for patients with previously untreated advanced non-small-cell lung cancer.