■ BACKGROUND AND OBJECTIVE: To evaluate the protective effect of different ophthalmic viscosurgical devices (OVDs) on corneal endothelial cells against relatively severe phacoemulsification damage in a rabbit model. ■ MATERIALS AND METHODS: Twenty-four rabbit eyes were randomly assigned to four similar groups: in three groups the aqueous humor was completely replaced by Visiol (TRB CHEMEDICA, München, Germany), Biolon (Bio-Technology General Ltd., Kiryat Malachi, Israel), and Viscoat (Alcon, Puurs, Belgium) and in the control group no OVD was applied. Endothelial cell counts were performed prior to initiating the study. All eyes were exposed to continuous 5 minutes of phacoemulsification. Endothelial cell counts were repeated 4 days postoperatively. squf; RESULTS: Viscoat showed the highest endothelial cell loss (30%), followed by Biolon (25%), Visiol (22%), and the control group (19%). None of the differences between the groups were found to be statistically significant, although they were within each group (P = .028). ■ CONCLUSION: None of the tested OVDs demonstrated protective effect on corneal endothelial cells in comparison to the control group. This model was found to be too aggressive for the demonstration of the protective effect of different OVDs even for hard cataract.