Advanced non-small-cell lung cancer (NSCLC) patients with poor performance status (PS) are less likely to respond to chemotherapy, or to have an improvement in survival, but more likely to experience toxicity. We retrospectively evaluated the efficacy and tolerability of gefitinib in patients with advanced NSCLC and very poor PS in Taiwan. Patients with stage IIIB, IV NSCLC with an Eastern Cooperative Oncology Group (ECOG) PS of 3-4 received oral gefitinib 250 mg once daily. Totally, 52 patients were included (25 men, 27 women). Forty-three patients (82.7%) were in a PS of 3. Tumor response rate was 25.0% (13/52). Tumor response rate to gefitinib was highest in chemonaive patients 38.1% (8/21) vs. failed 1 chemotherapy regimen 13.3% (2/15) vs. failed 2 or more chemotherapy regimens 18.8% (3/16), p = 0.015. The median overall survival was 2.5 months (response group 9.1 months, stable disease 3.1 months, and progressive group 0.8 month, p < 0.001). Adverse events, mainly skin reactions and diarrhea, were generally mild (grade 1 or 2) except paronychia and acne. Thus, gefitinib has clinically antitumor activity and good tolerability in Taiwan patients with advanced NSCLC and very poor performance status, with a higher response rate than that seen Europe or in European heritage Americans. Chemonaive patients responded better than patients with prior chemotherapy. Formal clinical trials are warranted to evaluate the role of gefitinib in this situation.