The purpose of this study was to determine the maximum tolerated dose and evaluate the dose-limiting toxicities of the gemcitabine/oxaliplatin combination in patients with advanced-stage solid tumors. Of the 48 enrolled patients, 35% had first-line, 23% had second-line, and 42% had third-line therapy. Patients received escalating doses of 1,000 to 1,600 mg/m2 gemcitabine on days I and 8 plus 60 to 120 mg/m2 oxaliplatin on day 8, every 21 days. The dose-limiting toxicities (first nine dose levels) were grade 4 neutropenia, grade 3 asthenia, and grade I to 3 neutropenia or thrombocytopenia. One hundred fifty-three cycles have been administered without any febrile neutropenia or toxic death. Grade 3-4 neutropenia and grade 3 thrombocytopenia were noted in 13 (9%) and seven (5%) cycles, respectively. Nonhematologic toxicity has been mild; the most common was grade 2 to 3 asthenia occurring in 29% of cycles. Among 30 evaluable patients, four partial responses have been observed (response rate, 13%). In this phase I study, the maximum tolerated dose of this drug combination has not yet been reached, although gemcitabine up to 1,600 mg/m2 (days I and 8) plus oxaliplatin up to 120 mg/m2 (day 8) was active and well tolerated, warranting further evaluation in phase II studies.