Objective: To determine if increasing paternal age has an adverse effect on pregnancy outcomes in paired donor egg recipients who received oocytes from the same donor in the same stimulation cycle., Design: Retrospective cohort study., Setting: Reproductive Medicine Center., Patient(s): The study included 154 recipients who received oocytes from a split donor oocyte cycle and received sperm from men in discrepant age groups (group A: <45 years old; group B: ≥45 years old)., Intervention(s): None., Main Outcome Measure(s): Implantation rate, pregnancy loss rate, pregnancy rate, and live birth rate., Result(s): The median paternal age was 41 years old for group A and 48 years old for group B. The pregnancy rate was 81% in group A compared with 69% in group B. The live birth rate was 65% in group A compared with 53% in group B. The rate of pregnancy loss was 19% in group A and 23% in group B. The implantation rate was 69% in group A compared with 66% in group B. The adjusted odds of pregnancy were found to be 65% lower for patients in the older partner age group (95% confidence interval [CI], 0.13, 0.95). The adjusted odds of live birth rate (odds ratio [OR], 0.45; 95% CI, 0.20, 1.00), implantation rate (OR, 0.91; 95% CI, 0.43, 1.92), and rate of pregnancy loss (OR, 1.5; 95% CI, 0.5, 4.5) favored the younger partner age group; however, these results were not statistically significant., Conclusion(s): In this model that controlled for oocyte quality to the greatest degree possible by using paired recipients from the same donor from the same stimulation cycle, we found that increased paternal age had a negative effect on pregnancy rates., (Copyright © 2021 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)