A clear clinical management pathway (conventional in vitro fertilization, IVF or intracytoplasmic sperm injection, ICSI) for treating patients with teratozoospermia is lacking. Here we conducted a retrospective study of fertility indices in 2,178 IVF/ICSI cycles in order to reevaluate clinical management of couples with isolated teratozoospermia (< 4% morphologically normal sperms and normal sperm concentration and motility with the standard of WHO-5).We strictly controlled external factors that could affect oocyte quality or endometrial receptivity to minimize the impact of confounders. Fertilization, total fertilization failure, embryo quality, blastocyst formation rate, and pregnancy rate were studied. Retrospectively, in conventional IVF cycles a significantly lower fertilization rate and higher total fertilization failure rate were observed in couples with isolated teratozoospermia as compared to couples with a normal semen profile. Furthermore, when ICSI was used to treat these teratozoospermic couples, improvement in fertilization was noted. However, the embryo quality, blastocyst formation rate, and pregnancy of couples with isolated teratozoospermia were not enhanced by ICSI. Multiple variable analysis showed that many factors including percentage of morphologically normal sperm are statistically correlated with fertilization rate and total fertilization failure in conventional IVF cycles. In addition the insemination method was correlated with fertilization rate in cases with isolated teratozoospermia. Further studies are warranted to compare outcomes of conventional IVF and ICSI in cases of isolated teratozoospermia, where less than 5 oocytes are retrieved.