To investigate the extent of long-term corneal endothelial loss after uneventful cataract surgery and the factors associated with decreases in corneal endothelial cell density (ECD). Retrospective case series. Patients who had undergone uncomplicated cataract surgery. This study comprised 81 eyes of 48 patients who had undergone cataract surgery >10 years previously by a single surgeon with the same intraocular lens and visited the outpatient clinic between January 2014 and February 2017. Long-term (≥10 years) changes in visual outcome and ECD after uncomplicated cataract surgery were evaluated. To analyze factors correlated with endothelial cell loss, preoperative biometric variables, including cataract grade, anterior chamber depth, axial length, and postoperative corneal edema, were evaluated. The mean ± SD preoperative and long-term postoperative ECD was 2793 ± 351.09 and 2148 ± 478.38 cells/mm2, respectively. The mean follow-up period was 11.08 ± 1.06 years and 10-year ECD loss rate was 20.62 ± 13.63%. Preoperative nuclear firmness was most statistically correlated with 10-year ECD loss (β-coefficient 0.394 [95% CI 3.402-9.448]; p < 0.001). The degree of postoperative corneal edema was also a significant predictive factor of 10-year ECD loss after cataract surgery (β-coefficient 0.378 [95% CI 2.854-8.358]; p = 0.002). Preoperative nuclear firmness and postoperative corneal edema were predictors of long-term (≥10 years) endothelial cell loss and severe endothelial cell loss after cataract surgery. It is important to remember that eyes with increased nuclear firmness have a significantly higher risk of long-term enhanced ECL.