Objective: To evaluate the effects of injection of 1:100,000 dilution adrenalin with sodium bisulfite preservative on the corneal endothelium in phacoemulsification cataract surgery. Methods: This retrospective study comprised 70 patients with age-related cataracts who had undergone phacoemulsification cataract surgery with intraocular lens (IOL) implantation without any surgical complications. In the adrenalin group, patients with intraoperative intracameral adrenalin use were included. The intracameral adrenalin was composed of 1mL of 1:100,000 dilution adrenalin with sodium bisulfite preservative. The control group included patients who underwent surgery without any intracameral adrenaline use. There were 36 patients in the adrenalin group and 34 patients in the control group. Corneal endothelial density, endothelial cell morphology, and endothelial cell area were measured via specular microscopy both preoperatively and 3 months after surgery. The 2 groups were compared with regard to changes in specular microscopy measurements. Results: The mean (± standard deviation) age was 66.51±8.32 years in the adrenalin group and 67.58±7.83 years in the control group. The difference in age between the 2 groups was not significant (p.611). The preoperative mean corneal endothelial cell density was 2,270±286 cells/mm2 in the adrenalin group and 2,226±260 cells/mm 2 in the control group, and the difference between the 2 groups was not statistically significant (p.550). In the adrenalin group, the postoperative mean corneal endothelial cell density was 2,191±268 cells/mm 2. Although the postoperative mean cell density was lower than the preoperative mean cell density, the difference between the 2 measurements was not statistically significant (p.117). In the control group, the postoperative mean corneal endothelial cell density was 2,169±272 cells/mm2, and the difference between the preoperative and postoperative measurements was not statistically significant (p.161). Comparisons of postoperative specular microscopy measurements between the adrenalin and control groups with regard to cell density, cell sizes, and cell shapes showed that there were no statistically significant differences in comparison of all parameters between the 2 groups. Conclusions: Intracameral injection of 1:100,000 dilution adrenalin with sodium bisulfite preservative is not toxic to corneal endothelium. © 2010 Informa UK Ltd.