The study was aimed to evaluate the feasibility of dose-intensive chemotherapy given on a weekly basis for 12 weeks. Seventeen [7 with limited disease (LD) and 10 with extensive disease (ED)] previously untreated patients with small-cell lung cancer (SCLC) were treated with the cisplatin, vincristine, doxorubicin, and etoposide (CODE) regimen. Recombinant human granulocyte colony-stimulating factor (rhG-CSF) was given to eight patients for the purpose of increasing the dose intensity. Overall response rate was 88%, with a 29% complete response. The median survival times were greater than 20.5 months for LD patients and 8.1 months for ED patients. Overall actual dose intensity was 88% of planned protocol. The major toxicity was myelosuppression. Fifteen patients (88%) had grade 3 or 4 leukopenia. Other problems were weight loss and worsening of performance status during the treatment. RhG-CSF significantly reduced leukopenic nadirs and shortened the neutropenic period. Our preliminary results indicate that 12 cycles of the CODE regimen on a weekly schedule is effective for SCLC, but is also associated with significant toxicity.