Endometrial receptivity plays a basic role in successful embryo implantation and pregnancy outcomes and can be assessed by many of non-invasive markers. Our study evaluated the impact of two of these markers specifically serum progesterone and endometrial thickness at embryo transfer day in prediction pregnancy outcomes on (60) patients attempting medicated frozen embryo transfer (FET) cycles. All patients were received sequential estrogen & progesterone medications for endometrial preparation then submitted to measurements of endometrial thickness (EMT) by transvaginal-ultrasound (TV-US) & serums progesterone (P) analysis at the embryo transfer day, thereafter day 3 verified-thawed embryos grades (A±B) were transferred. Compacted (decreased) EMT was seen in 48.3% of patients with higher pregnancy rate (PR) of 58.6%t than non-compacted EMT (no change or increased) which was seen in 51.7% of patients with (PR) of 29.0%, (P value=0.021). However ongoing pregnancy rate (Ong PR) not differed significantly between both groups (44.8% in compacted vs 25.8% in non-compacted, P value=0.053), also the means of serum P not differed between pregnant and non-pregnant patients (P value=0.374). ROC curves for Ong PR prediction in relations to endometrial compaction & serum progesterone at embryo transfer day were poor (AUC= 0.630, & AUC=0.576, respectively). This study suggested that endometrial compaction or serum P levels measurements at embryo transfer day were poor predictors for ongoing pregnancy where any kind of EMT changes (decreased or not) seen after P administration not significantly affect pregnancy outcomes in frozen-thaw cycles of cleavage stage embryos transfer.