Gefitinib (Iressa; AstraZeneca Pharmaceuticals, Wilmington, DE) is an oral epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) with favorable toxicity and antitumor activity in pretreated patients with non-small cell lung cancer (NSCLC). The purpose of this study was to evaluate the toxicity and efficacy of gefitinib in patients with advanced NSCLC treated at our institution as part of an expanded access protocol; 112 patients with advanced NSCLC were entered. All patients had failed at least one previous chemotherapy regimen, or were not suitable for any systemic chemotherapy because of poor performance status (PS), or were ineligible for other clinical trials. Therapy consisted of gefitinib 250 mg orally once daily; 10.5% (95% CI 5.3-17.9%) of patients achieved partial/minimal response (PR/MR) and 29.5% (95% CI 21.0-39.2%) had stable disease (SD), resulting in a disease control rate (PR/MR+SD) of 40% (95% CI 31-50%). The median duration of treatment for all patients was 12 weeks (range 2-116 weeks) and for patients achieving disease control 28 weeks (range 8-116). Nine patients received gefitinib for more than 1 year. Median survival was 30 weeks. Symptoms were improved in 36% of evaluable patients, and 64% of patients who achieved disease control experienced improvement of their disease related symptoms. Adverse events were generally mild and consisted mostly of skin rash (48%) and diarrhea (38%). A statistically significant association was observed between disease control and skin rash (p = < 0.001), nonsmoking status (p = 0.048), and symptom improvement (p = 0.001). The disease control rate was not statistically associated with histology, PS, gender, or number of prior treatments. In addition, longer survival was significantly associated with skin rash (p = < 0.001) and symptom improvement (p = < 0.001). Gefitinib demonstrated relevant clinical activity and a favorable toxicity profile in pretreated patients with advanced NSCLC. The development of toxicity was associated with a favorable response. In addition, a history of never having smoked seems to predict a higher efficacy of gefitinib.