Amrubicin, a third-generation synthetic anthracycline agent, has favorable clinical activity and acceptable toxicity for the treatment of patients with non-small cell lung cancer (NSCLC) and small cell lung cancer. We conducted this study to evaluate the efficacy and safety of amrubicin for advanced NSCLC patients as a third- or fourth-line therapy. Eligible patients had recurrent or refractory advanced NSCLC after second- or third-line therapy. Patients received amrubicin, 35 mg/m(2) i.v. on days 1-3 every 3 weeks. The primary endpoint was the disease control rate (DCR). Secondary endpoints were the overall survival (OS) time, progression-free survival (PFS) time, response rate, and toxicity profile. Of the 41 patients enrolled, 26 received amrubicin as a third-line and 15 received it as a fourth-line therapy. The median number of treatment cycles was two (range, 1-9). Objective responses were complete response (n = 0), partial response (n = 4), stable disease (n = 21), progressive disease (n = 15), and not evaluable (n = 1), resulting in a DCR of 61.0% (95% confidence interval, 46.0%-75.9%). The overall response rate was 9.8% (95% confidence interval, 0.6%-18.8%). The median PFS interval was 3.0 months, median OS time was 12.6 months, and 1-year survival rate was 53.7%. Grade 3 or 4 hematological toxicities were neutropenia (68%), anemia (12%), thrombocytopenia (12%), and febrile neutropenia (17%). Nonhematological toxicities were mild and reversible. No treatment-related deaths were observed. Amrubicin showed significant clinical activity with manageable toxicities as a third- or fourth-line therapy for patients with advanced NSCLC. This study provides relevant data for routine practice and future prospective trials evaluating third- or fourth-line treatment strategies for patients with advanced NSCLC.