Objective: To determine the effect-of age on sperm fecundability using oocyte donation as an in vivo model. Setting: Oocyte donation and IVF programs at the Instituto Valenciano de Infertilidad. Patients: Two-hundred forty couples undergoing 345 cycles of ovum donation, who were recipients of 298 donors, Design: Retrospective study in which four groups of oocyte donation cycles were established according to age of the male providing the semen sample: group 1 (n = 31) <30 years; group 2 (n = 195) 31 to 40 years; group 3 (n = 98) 41 to 50 years; group 4 (n = 21) >51 years, the oldest being 64 years. All donated oocytes were obtained from patients < 35 years old. Main Outcome Measurements: Male age, sperm characteristics (volume, concentration, motility, morphology), fertilization, embryo quality, pregnancy, implantation, and abortion rates among recipients. Results: Similar sperm characteristics in fresh as well as after preparation for NF were observed among males of different-ages. Fertilization, embryo quality, pregnancy, and implantation were similar among the established groups. The mean age of the females included in each group significantly increased from group 1 to group 4. Conclusions: Age (up to 64 years) does not affect sperm characteristics or its ability to fertilize human eggs. Similarly, embryo development in vitro as well as implantation in recipient uteri are not affected by age of the male providing the semen sample.