Objective: To evaluate the impact of the oxytocin receptor antagonist atosiban on implantation and pregnancy rates after first ICSI trial in good prognosis cases. Design: Randomised controlled trial. Materials and Methods: The study included 182 women, prepared for first trial of ICSI for male or tubal factor infertility, using long agonist protocol, were randomized to receive 7.5 mg atosiban or placebo IV 20 minutes before embryo transfer (ET). Results: Fifty-eight (63.7%) cases had ongoing pregnancy in the study group while 44 (48.4%) cases had ongoing pregnancy in control group and this was statistically significant (p = 0.037). Implantation rates were 45.20%, and 34.69%, respectively, which was also statistically significant (p = 0.045). All of the intermediate cycle parameters were also comparable. Conclusion: Atosiban in the given dose and regimen improved both implantation and on going pregnancy rates in good prognosis cases undergoing first ICSI trial and blastocyst stage embryo transfer.