Résumé : Objective: To compare ICSI with IVF using two insemination concentrations in moderate male infertility and to compare these data with other randomized controlled trials (RCTs). Design: Prospective, randomized, controlled trial and meta-analysis. Setting: University-based tertiary referral center. Patient(s): Seventy-three couples undergoing ART. Intervention(s): In one IVF group a standard insemination concentration of 0.2 × 106/mL was used, whereas in the other group a high insemination concentration (HIC) of 0.8 × 106/mL was used. Each protocol was compared with ICSI on sibling oocytes. Main Outcome Measure(s): Fertilization, fertilization failure, and embryonic development. Result(s): The overall fertilization rate was significantly lower after standard IVF than after ICSI: 37.4% vs. 64.3%. Where HIC IVF was used, the overall fertilization rate was not significantly different from that after ICSI: 59.6% vs. 67.6%. Eight randomized controlled trials were selected and reviewed together with the present randomized controlled trial by meta-analysis. The risk ratio for an oocyte to become fertilized was 1.9 (95% confidence interval of 1.4 to 2.5) in favor of ICSI, and 3.1 ICSI cycles may be needed to avoid one complete fertilization failure after conventional IVF (95% CI of 1.7 to 12.4). Conclusion(s): The data from this study and the meta-analysis show that ICSI is a more efficient technique in terms of fertilization, but not in comparison with HIC IVF. © 2002 by American Society for Reproductive Medicine.