Background: The present study evaluated the fertilization outcomes by intra-cytoplasmic sperm injection (ICSI) technique with oligoastheno-zoospermic (OAZ) compared to normozoospermic (NZ) semen. Purpose: To find the fertilizing capability of human sperm in oligo-asthenozoospermic and normozoospermic semen samples. Methods: Fresh semen ejaculates belonging to NZ and OAZ groups (n=50 in each group) patients attending the infertility clinics were evalu-ated for semen volume, sperm motility, and sperm concentration. Ferti-lization rates with ICSI along with post-capacitation motility and con-centration were studied in both groups. Results: The motility and concentration in fresh semen samples patients of the NZ group (32.44±1.50%, 71.96±6.45 M/ml, respectively) were significantly (P<0.05) higher compared to the OAZ group (26.76±1.38, 10.31±0.48 M/ml, respectively).However, the results of our study re-vealed similar fertilization rates in-vitro by ICSI in the NZ (98%) and OAZ (98%) groups. Conclusion:The in-vitro processing by the ICSI technique is an effective approach to achieving good fertilization rates in sub-fertile males.