To determine if GnRH agonist (triptorelin) administration supporting luteum phase in transferring freeze to thaw embryos (F.E.T) improves clinical outcomes. Methods and Designs: I have carried out analysis of a Retrospective Cohort and analyzed 3515 cycles of receiving FET at department of reproductive medicine of our hospital from February 2018 through December 2021. The Patients were divided into GnRH-a (triptorelin +existing treatment) group and No GnRH-a (existing treatment without Triptorelin) group. There were 1033 and 2485 cases in above groups respectively. Live births rates (L.B.R) and clinical pregnancies rates (C.P.R) were contrasted in two groups.