OBJECTIVE To compare the changes in endothelial cell density (ECD) in post-penetrating keratoplasty (PKP) patients after cataract extraction with phacoemulsification or planned extracapsular cataract extraction (ECCE). METHODS Haydarpasa Numune Education and Research Hospital, Ophthalmology Clinic, Istanbul, Turkey. METHODS Clinical trial. METHODS Eyes with hard nuclear cataract that had previous PKP were randomly assigned to have phacoemulsification or ECCE. Noncontact specular microscopy was performed preoperatively and 1, 3, and 6 months postoperatively. RESULTS Twenty-six eyes of 26 patients were enrolled (14 phacoemulsification; 12 ECCE). Six months postoperatively, the mean corneal ECD was statistically significantly lower in the phacoemulsification group (1869.50 cells/mm(2) ± 158.05 [SD]) than in the ECCE group (1996.00 ± 127.96 cells/mm(2)) (P=.024). The mean percentage of endothelial cell loss at 6 months was 20.3% and 12.7%, respectively (P<.05). In both groups, there was no significant difference in the percentage hexagonality between preoperatively and postoperatively (P>.05). CONCLUSIONS Extracapsular cataract extraction seemed to cause less endothelial cell damage than phacoemulsification in post-PKP patients with hard nuclear cataract.