Small cell lung cancer with interstitial lung disease (ILD-SCLC) is difficult to treat because of the risk of fatal pneumonitis. Our study aims to evaluate the validity of topotecan (TOP) as chemotherapy for patients with relapsed ILD-SCLC. Overall survival was compared between TOP and other drugs as second-line treatments for ILD-SCLC patients. Forty-seven patients began chemotherapy and second-line treatment was administered in 48.5% of relapsed cases. The response rate of TOP for second-line therapy was 16.7%. Hematologic toxicities were grade 4 anemia, grade 3 neutropenia and grade 3 thrombocytopenia. Mild pulmonary toxicity was observed in 1 case. Patients receiving TOP as second-line treatment showed no significant difference in survival when compared to patients who underwent other regimens (median survival time 179 vs. 76 days; p =0.76). TOP is a well tolerated drug and is a viable candidate for second-line treatment of ILD-SCLC patients.