Whereas non-small cell lung cancer (NSCLC) comprises 80% of all lung cancer cases, effective prolongation of survival in NSCLC patients using currently available combination chemotherapy has been problematic. Use of dose-intensive chemotherapy along with hematopoietic growth factor support is an attractive, albeit experimental, alternative. We have conducted a phase I study to determine the maximum tolerated dose of etoposide in the ifosfamide/carboplatin/etoposide (ICE) regimen when used with granulocyte-macrophage colony-stimulating factor (GM-CSF) support. Twenty-three patients with solid tumors refractory to standard treatment who had not received previous platinum-containing chemotherapy or for whom there was no generally accepted curative therapy were treated. We present results obtained in 11 patients with previously untreated stage IV NSCLC. The use of ICE plus GM-CSF demonstrated promising activity in this group of patients; the overall response rate was 64%, and median survival was 10.0 months. The maximum tolerated dose of this regimen is 900 mg/m2 etoposide in combination with 5 g/m2 ifosfamide, 400 mg/m2 carboplatin, and 5 micrograms/kg/d GM-CSF.