The physical compatibility of Hextend (6% hetastarch in lactated electrolyte injection, Abbott Laboratories, Abbott Park, Illinois) with 100 selected other drugs during simulated Y-site injection was evaluated by means of visual observation, turbidity measurement, and electronic particle content assessment when appropriate. Five-milliliter samples of Hextend injection were combined with 5 mL of 100 other test drugs that included anti-infectives, analgesics, antihistamines, diuretics, steroids, and other supportive care drugs undilted or diluted in 5% dextrose injection (or if necessary to avoid incompatibility of the secondary drug with the diluent, 0.9% sodium chloride injection). Visual examinations were performed with the unaided eye in normal diffuse fluorescent light and by means of a Tyndall beam (a high-intensity monodirectional light beam) to enhance visualization of small particles and low-level turbidity. The turbidity of each sample was measured as well. The particle content of samples with no visible incompatibility was measured. Evaluation of the samples was performed initially and at 1 and 4 hours after preparation. Ninety-seven of the 100 test drugs were compatible with Hextend injection during the 4-hour observation period. However, amphotericin B and diazepam resulted in precipitation, and sodium bicarbonate resulted in microcrystalline precipitation. Hextend injection should not be administered simultaneously with those incompatible drugs. Other drugs previously reported to be incompatible with 6% hetastarch in 0.9% sodium chloride injection were not found to be incompatible with Hextend.