PURPOSE To determine the maximum-tolerated dose of monthly docetaxel combined with fixed-dose weekly gemcitabine and describe the dose-limiting toxicities (DLTs) of the combination. PATIENTS AND METHODS Patients with refractory solid tumors were treated with gemcitabine days 1, 8, and 15 every 4 weeks at a fixed dose of 800 mg/m2. Two docetaxel administration schedules were studied, with the drug administered either day 1 or day 15 at doses of 45, 60, 75, and 100 mg/m2 per cycle. RESULTS Forty patients received 132 cycles of chemotherapy. On the day-1 schedule, the maximum-tolerated docetaxel dose was the highest planned dose of 100 mg/m2 with two DLT episodes among 12 patients treated with 34 cycles at this dose level. On the day-15 schedule, delivery of the planned docetaxel doses was not feasible because of thrombocytopenia and hepatic dysfunction. Hematologic toxicities included grade 4 neutropenia in 16 patients, with three episodes of febrile neutropenia; grades 3 to 4 thrombocytopenia in nine patients; and anemia that required RBC transfusions in 10 patients. For patients treated at the highest docetaxel dose level, myelosuppression was not dose limiting and only one of 34 cycles was complicated by febrile neutropenia. The most common nonhematologic toxicities were asthenia, flu-like symptoms, and fluid retention. Antineoplastic activity was noteworthy, with partial responses in nine of 21 patients with pretreated non-small-cell lung cancer (NSCLC; 43%; 95% confidence interval, 22 to 66), in four of seven patients with breast cancer, and in one patient with esophageal adenocarcinoma. CONCLUSION Gemcitabine 800 mg/m2 days 1,8, and 15 can be safely combined with docetaxel 100 mg/m2 day 1 of a 28-day cycle. The observed antitumor activity warrants phase II evaluation.