OBJECTIVE:To assess fertilization, implantation, and pregnancy rates in patients undergoing ICSI using fresh and cryopreserved sperm from ejaculated semen samples. DESIGN:Retrospective study. SETTING:Academic and private medical centers. PATIENT(S):One hundred fifty-eight patients. INTERVENTION(S):Intracytoplasmic sperm injection. MAIN OUTCOME MEASURE(S):Fertilization, implantation, and pregnancy rates were evaluated; 61 cycles of ICSI were performed with cryopreserved and 79 cycles of ICSI were performed with fresh spermatozoa. Also, we divided the outcomes according to the semen characteristics, normozoospermia, oligozoospermia, asthenozoospermia, and oligoasthenozoospermia. RESULT(S):Overall, normal-fertilization rates were higher using fresh sperm (73.8%) compared with cryopreserved sperm (68.7%). Cycles performed in patients with normozoospermia or oligozoospermia had similar fertilization, implantation, and pregnancy rates using fresh or cryopreserved sperm. When asthenozoospermic and oligoasthenozoospermic semen samples were used, the normal-fertilization rate was higher with fresh sperm compared with cryopreserved sperm. However, implantation and pregnancy rates were similar in fresh and cryopreserved sperm samples from patients with asthenozoospermia or oligoasthenozoospermia. CONCLUSION(S):Semen with abnormalities in the motility may be more susceptible to sperm cryopreservation damage, resulting in lower fertilization rates. However, once the oocyte is fertilized, implantation and pregnancy rates are similar to those in patients with oligozoospermia and normozoospermia.