Background/Aims. Topotecan and docetaxel are active agents in the treatment of various malignant diseases. Both drugs cause dose-limiting hematologic toxicity. This study defines the maximum tolerated dose (MTD) and dose-limiting toxicity of weekly topotecan when administered in combination with docetaxel 25 mg/m2 given day 1, 8,15 every 28 days. Methods. Thirteen patients were enrolled. Median age was 62 years. Majority of the patients had lung cancer. Results. The maximum tolerated dose was docetaxel 25 mg/m2 and topotecan 3 mg/m2 administered weekly. Dose-limiting toxicity was febrile neutropenia. Eight patients developed at least grade 3 neutropenia in all cycles. Non-hematologic toxicities were mild. No objective responses were noted. Two patients with non-small cell lung cancer had stable disease as a best response. Conclusion. Combination docetaxel and topotecan given weekly is tolerable. The recommended phase II dose is docetaxel 25 mg/m2 and topotecan 3 mg/m2 day 1, 8, 15 every 28 days.