The chemical stabilities of cefoperazone and ceftazidime solutions in 5% dextrose and 0.9% sodium chloride injections have been studied using high-performance liquid chromatography methods. The solutions of cefoperazone were stable for 8 days (loss in potency of less than 10%) at 25 degrees C, for at least 80 days at 5 degrees C and for at least 96 days at -10 degrees C. The ceftazidime solutions were stable for only 2 days at 25 degrees C, for 21 days at 5 degrees C (28 days in normal saline) and for 90 days at -10 degrees C. Thawing the frozen solutions using a microwave oven did not cause degradation.