The isometric method of assessment of the contractility of uterine strips in vitro makes it possible to follow up systematically the response of smooth uterine musculature to oxytocin and to test the effect of selected preparations on this process. In the submitted work the author investigated the effect of methyloxytocin, magnesium sulphate, seduxene, phenergan, plegomazine and DH-ergotoxin on the uterine contractions of strips of rat and human uteri ted. Based on the results of model experiments in vitro, the author discusses the effect of the mentioned substances on the spasmogenic activity of oxytocin.