Aims & Objectives: The study aimed to find out any significant difference between pregnancy rates (PR) of infertile couples undergoing IUI with frozen thawed donor sperm at interval of 24 hrs(Group A) & 36 hrs (Group B) of HCG injection. Material & Method: 300 women were selected for donor intra uterine insemination (IUI-D). Ovulation induction was done with Clomiphene citrate (CC) or Letrozole from D2 to D6. Injection HCG 5000 IU was given intramuscularly when the dominant follicle reached = 18mm size on follicular study. IUI was done at 24 hours interval in 150 women (group A) and at 36 hours interval in other 150 women (Group B).