The stability of ofloxacin was evaluated in 10 different infusion fluids under various storage conditions. Solutions of ofloxacin (0.4 mg/mL and 4.0 mg/mL) were prepared in (1) 0.9% sodium chloride injection; (2) 5% dextrose injection; (3) 5% dextrose and 0.9% sodium chloride injection; (4) 5% dextrose and lactated Ringer's injection; (5) 5% sodium bicarbonate injection; (6) Plasma-Lyte 56 and 5% dextrose injection; (7) 5% dextrose, 0.45% sodium chloride, and 0.15% potassium chloride injection; (8) 1/6 M sodium lactate injection; (9) water for injection; and (10) 20% mannitol injection. Each solution was injected into polyvinyl chloride bags and stored at (1) 24 degrees C for 3 days, (2) 5 degrees C for 7 days, (3) 5 degrees C for 14 days, (4) -20 degrees C for 13 weeks and then 5 degrees C for 14 days, or (5) -20 degrees C for 26 weeks and then 5 degrees C, for 14 days. Samples were assayed initially and after storage by high-performance liquid chromatography and examined for visual clarity, pH, turbidity, and particulates. Ofloxacin was stable in all solutions and under all storage conditions. All of the solutions were clear, pH was stable, and particulate-matter counts were acceptable under all storage conditions (except for the 20% mannitol solution, which formed crystals at 5 degrees C and -20 degrees C). An injectable formulation of ofloxacin was stable for at least 3 days at 24 degrees C, 14 days at 5 degrees C, and 26 weeks at -20 degrees C in all tested infusion fluids. Crystals formed in refrigerated or frozen solutions prepared with 20% mannitol injection.