The visual and chemical compatibility of esmolol hydrochloride mixed with aminophylline, heparin sodium, bretylium tosylate, or procainamide hydrochloride in 5% dextrose injection was studied. Esmolol hydrochloride 600 mg was injected into polyvinyl chloride bags containing 100 mL of 5% dextrose injection with aminophylline 100 mg, heparin sodium 5000 units, bretylium tosylate 100 mg, or procainamide hydrochloride 400 mg. All admixtures were prepared in triplicate and stored at room temperature under fluorescent light. Esmolol concentrations were measured with high-performance liquid chromatography at 0, 2, 4, 8, and 24 hours. Samples were also examined for precipitate formation and pH and color changes by using visual, microscopic, and spectrophotometric methods. No detectable changes in color or pH and no particulate formation were observed in any of the sample bags. Esmolol concentrations varied by less than 5% throughout the 24-hour study period. Esmolol hydrochloride was visually compatible and chemically stable for at least 24 hours when mixed with aminophylline, heparin sodium, bretylium tosylate, or procainamide hydrochloride in polyvinyl chloride bags containing 5% dextrose injection.