Résumé : The present study evaluates the usefulness of the sub-zonal insemination (SUZI) for patients with previous IVF failures or affected by severe oligoasthenoteratozoospermia and the necessity of pre-treatment semen analysis. Design: Twenty-five patients underwent 43 cycles of either SUZI or alternate SUZI/IVF procedures according to semen characteristics. Results: Among the 571 retrieved oocytes, 398 were microinjected and 173 were treated by IVF. Among the microinjected oocytes, 19% fertilized (12% 2PN; 7% 3PN) and 96% of the 2PN oocytes developed into embryos. Thirty-one embryo transfers were performed, 8 pregnancies were obtained and 7 embryos were cryopreserved. The 2 PN rates in SUZI and IVF procedures in the same cycle were not significantly different. The analysis of the different semen samples obtained before and during the treatment reveals that the semen quality varies in such a way that the decision of the adequate microinjection strategy to follow should only be taken according to the semen quality at the day of treatment. Conclusion: SUZI is not a satisfactory technique for treatment neither in case of previous IVF failures nor for severe oligoasthenoteratozoospermia.