The luteal phase (LP) in the fresh ICSI cycle is insufficient, adequate LP support is one of the approved treatments for improving implantation and pregnancy rates. It is generally known that the LP is inadequate after ovarian stimulation due to negative from supra-physiological blood levels of steroids released by numerous corporal luteal, LH concentrations are low during the luteal phase. In this study, patients were divided into two groups: (40) patients as study group; those who received GnRHa (Decapeptil 0.1 mg), three days after embryo transfer, in addition to conventional luteal phase support (LPS) in the LP to increase the implantation and pregnancy rate in IVF; and their control group (40) received standard LPS only. On the second day of stimulation, blood samples for FSH, LH, TSH, E2, and prolactin were taken. On the day of ovulation induction, measure E2, progesterone, and LH; and on the day of embryo transfers, measure progesterone and LH. The overall characteristics of the patients in both groups were not significantly different. There was also no significant change in the number of total oocytes, mean of metaphase II oocytes percent, cleavage rate, grade I embryo percent, or serum hormones level between the study and control groups (p > 0.05). GnRH agonist treatment in the luteal phase improves clinical pregnancy and implantation rate in fresh ICSI cycles but is not statistically significant.