Gefitinib has modest activity with an overall response rate of 11-18% in patients with metastatic non-small cell lung cancer (NSCLC) who have had progressive disease following platinum containing chemotherapy. However, the efficacy of gefitinib in previously untreated metastatic NSCLC is not known. We retrospectively analyzed the efficacy of gefitinib as a first line therapy in 26 patients with advanced NSCLC enrolled in the expanded access program. Patients received gefitinib 250 mg a day orally if they had a poor performance status (PS) or if they refused cytotoxic chemotherapy. Treatment was continued as long as there was no evidence of disease progression or unacceptable treatment related toxicities. The characteristics of 25 evaluable patients enrolled between the period of May 2001 and August 2002 include: 15 women, 10 men; median age 73 years (range 56-86), 81% had an ECOG performance status of two. Only one patient had a partial response and 32% had stable disease as their best response for a disease control rate of 36%; 32% of patients had disease control lasting 5 months or longer. The median overall survival and progression-free survival (PFS) were 14.1 and 2.9 months, respectively. Toxicities were minimal and included rash and diarrhea. Gefitinib was well tolerated and had interesting activity in previously untreated patients with advanced NSCLC.