In this work we studied the effect of fetal membranes on basal and stimulated uterine contractions by PGF2 a and oxytocin, we used the isolated uterine horns of non pregnant and pregnant albino rats, and uterine contractions were recorded by the two channels ossillograph, that record the isotonic contractions throughout the experiments, we found that fetal membranes induce an inhibitory effect on basal uterine contractions of non pregnant and pregnant uterine horns, also PGF2 or induce an increased uterine contractions of both non pregnant and pregnant uterine horns, by increasing Ca+2 injlux from extracellular to intracellular compartment ,so this effect was inhibited by fetal membranes. Oxytocin also induce an increased uterine contractions of both pregnant and non pregnant uterine horns, and this effect was not blocked by fetal membranes. as oxytocin act through phospholipase - C-inositol lipid - IP3 signal transducing pathway to mobilize intracellular Ca+2 from the sarcoplasmic reticulum, so it can not be blocked by fetal membranes.