Oxytocin is a small peptide hormone with multiple sites of action in human body.It regulates a large number of reproduction-related processes in all species.Par-ticularly important is its ability to stimulate uterine contractility.This is achievedby multiple mechanisms involving sarcoplasmic reticulum Ca~(2+)release and sensi-tization of the contractile apparatus to Ca~(2+).In this paper,we review the datapublished by us and other groups on oxytocin-induced modulation of uterinecontractility.We conclude that sensitization of contractile apparatus to Ca~(2+)isthe most relevant physiological effect of oxytocin on human myometrium. Oxytocin is a small peptide hormone with multiple sites of action in human body. It regulates a large number of reproduction-related processes in all species. Par- ticularly important is its ability to stimulate uterine contractility. This is achieved by multiple mechanisms involving sarcoplasmic reticulum Ca ~ (2+) release and sensitization of the contractile apparatus to Ca ~ (2 +). In this paper, we review the datapublished by us and other groups on oxytocin-induced modulation of uterinecontractility. We conclude that sensitization of contractile apparatus to Ca ~ (2+) is the most relevant physiological effect of oxytocin on human myometrium.