Intrauterine pressures (IUP) were recorded simultaneously at the fundus, the isthmus, and cervix uteri by means of three micro-transducers (in 20 healthy, nonpregnant women, and in 5 patients with severe, primary dysmenorrhoea). Recordings were performed during the first 3 days of the menstrual cycle. Both incoordinate and coordinated myometrial activity was recognized. When coordination was present, the contraction wave as a rule started in fundus and was propagated towards the isthmus and cervix. Pinching and/or palpation of the cervix elicited retrograde contractions, i.e. the contraction wave started in the cervix and moved towards the fundus. It was frequently observed that during vigorous contractions of the fundus, the pressure increase in the isthmus was small; in some cases even a decrease in pressure occurred in this region. The pressure recording technique functioned perfectly during all recordings and seems to facilitate detailed studies of myometrial activity in the non-pregnant uterus.