Objective: To determine whether male age influences embryo development and reproductive potential in assisted reproductive technology cycles. Design: Retrospective cohort analysis. Setting: Private IVF center. Patient(s): One thousand twenty-three male partners participating in anonymous oocyte donation cycles. Intervention(s): Infertile couples undergoing 1,023 anonymous oocyte donation cycles. Main Outcome Measure(s): Live birth rate. Result(s): A significant increase in pregnancy loss, decrease in live birth, rate, and decrease in blastocyst formation rate were noted in men >50 years of age. There was no significant difference in implantation rate, pregnancy rate, or early embryo development through the cleavage stage (demonstrated by fertilization rate, embryo cleavage rate, percentage of nonfertilized or polyspermic embryos, rate of embryo arrest, or seven or more cell embryo development on day 3). Men >= 45 years of age had significantly more semen volume and more motile sperm than men >45 years of age. There was no significant change in sperm morphology or concentration. Conclusion(s): After controlling for female age with use of the donor oocyte model, male age >50 years significantly affected pregnancy outcomes and blastocyst formation rates. Semen volume and total motility decreased with increasing male age. initial embryo morphology through the cleavage stage was not affected.