['To evaluate the effects of sperm placement during ICSI relative to the M-II spindle location on fertilization and preimplantation development.', 'Retrospective analysis of oocyte fertilization and embryo development with respect to sperm deposition site during ICSI.', 'A program of IVF-ET.', 'Seven hundred seventy-six patients.', 'Egg quality, sperm deposition site, and polar-body position were recorded during ICSI; fertilization was assessed on day 1; embryo development was evaluated on days 2 and 3.', 'Fertilization, embryo development, and implantation rates.', "Normal fertilization is not affected by polar-body orientation, with the exception of a significantly lower fertilization rate from a 9 o'clock polar-body orientation. Injections with the polar-body positioned at 7 or 11 o'clock result in the greatest number of high-quality embryos, significantly more than the adjacent 6 or 12 o'clock polar-body orientations and irrespective of oocyte anomaly frequency. Embryos originating from the 7 or 11 o'clock polar-body category implant at a higher rate, although the data are not significant."] Does sperm deposition site during ICSI affect fertilization and development?