A prospective, randomized, observer-marked study was conducted to compare corneal endothelial and intraocular pressure (IOP) changes after cataract surgery with the viscoelastic agents Amvisc Plus and Viscoat. Forty-nine patients (50 eyes) who had uncomplicated phacoemulsification and implantation of a posterior chamber intraocular lens were randomly assigned to either Amvisc Plus (25 eyes) or Viscoat (25 eyes) groups. Surgical technique was rigidly standardized in all cases. No significant difference in endothelial parameters or postoperative IOPs measured at 24 hours, one week, and two months was detected by analysis of variance between the Amvisc Plus and the Viscoat groups. Visualization was difficult with Viscoat because of its tendency to retain bubbles. Phacoemulsification energy was related to a loss of endothelial density, regardless of the viscoelastic used. The postoperative beta blocker may have contributed to the lower average postoperative IOP than has been reported.