The compatibility and stability of netilmicin sulfate in a concentration of 3 mg/ml in 37 intravenous injections and in 5% dextrose and 0.9% sodium chloride injection with 26 commonly used additives were studied. Compatibility between an intravenous administration set and selected admixtures were also evaluated. The admixtures were stored at 4 and 25 degrees C for seven days. After mixing and on days 1, 3, and 7, all admixtures were evaluated for netilmicin potency, pH, color, osmolarity, and clarity. A microbiological assay was used to measure netilmicin potency. No changes in netilmicin potency, pH, osmolarity, color, or clarity were observed in any of the 37 netilmicin sulfate admixtures. Similarly, no changes in pH, osmolarity, or clarity were seen in the admixtures of netilmicin sulfate with a second additive. Netilmicin activity was retained for seven days in 22 of the 26 admixtures with a second additive. Netilmicin sulfate in admixtures with multivitamin injection or vitamin B complex (Upjohn) was stable for only one day; with diphenhydramine hydrochloride or neostigmine methylsulfate, for only three days. No incompatibilities between the intravenous infusion set and admixtures of netilmicin sulfate were apparent. Netilmicin sulfate injection is compatible and stable for at least seven days stored at 4 and 25 degrees C when mixed in 37 intravenous injections, and when mixed individually with 22 additives in 5% dextrose and 0.9% sodium chloride injection.