The stability of vancomycin hydrochloride mixed with 5% dextrose and 0.9% sodium chloride injections was studied. Vancomycin hydrochloride powder was mixed with each of the two diluents in final concentrations of 5 mg/mL. Duplicate samples of each admixture were divided into four parts and stored at 24 degrees C in glass and in plastic i.v. bags for 17 days and at 5 degrees C and -10 degrees C in glass for 63 days. To additional samples, hydrochloric acid or phosphate buffer was added; these were stored at 24 degrees C for 17 days. At various storage times, clarity and pH of the samples were recorded and vancomycin concentrations were measured in triplicate by high-performance liquid chromatography. Except for the buffered samples, all solutions remained clear and pH was unchanged. Vancomycin concentrations decreased less than 6% during 17 days at room temperature. In the refrigerated and frozen samples, vancomycin concentrations decreased less than 1% throughout the study. Vancomycin hydrochloride is stable in admixtures with 5% dextrose injection and 0.9% sodium chloride injection for 17 days at 24 degrees C and for 63 days at 5 degrees C and -10 degrees C.