Cefazolin and cefuroxime sodium are often used as antibiotic infusions for hospitalized patients. Because advance preparation of these intravenous solutions is efficient, the stability of both antibiotics stored at 4 degrees C in polyvinyl chloride (PVC) bags was studied. Five bags of solutions containing either 1 g of cefazolin sodium or 1.5 g of cefuroxime sodium per 100 ml of 5% dextrose were studied for 1 month by high-performance liquid chromatography (HPLC), visual inspection and pH measurement. No colour change or precipitation was observed. The pH values of both drugs increased significantly over the period of study. Based on a shelf-life of 90% residual potency, the cefuroxime sodium concentration was stable for 13 days when stored at 4 degrees C, and the cefazolin sodium concentration was stable for at least 30 days at 4 degrees C. Within these limits, both antibiotics may be prepared in advance by a centralized intravenous admixture service.