OBJECTIVE: To evaluate the physical compatibility and chemical stability of paclitaxel at concentrations of 300 and 1200 μg/mL with doxorubicin hydrochloride 200 μg/mL in NaCl 0.9% injection and dextrose 5% injection over 7 days at 4, 23, and 32 °C. DESIGN: The test samples were prepared in polyolefin bags of the infusion solutions at the required drug concentrations. Evaluations were performed initially and after 4 hours, and 1, 3, 5, and 7 days of storage at 4, 23, and 32 °C for physical and chemical stability. Physical stability was assessed by using visual observation in normal fluorescent light and a high-intensity monodirectional light beam. In addition, turbidity and particle content were measured electronically. Chemical stability of the two drugs was evaluated by using two stability-indicating HPLC analytic techniques. RESULTS: All samples were physically stable through 1 day. However, microcrystalline precipitation of paclitaxel occurred within 3 days in some samples and within 5 days in all samples. Paclitaxel concentrations remained at more than 97% in all samples throughout the study. Doxorubicin hydrochloride also was stable throughout the study period, remaining above 90% in all samples at all storage temperatures. CONCLUSIONS: Admixtures of paclitaxel 300 and 1200 μg/mL with doxorubicin hydrochloride are limited in their utility time by paclitaxel microcrystalline precipitation. All combinations were physically and chemically stable for at least 24 hours at 4, 23, and 32 °C.