The nonpregnant uterus shows uterine activity throughout the menstrual cycle. This uterine activity was detected both by single strep tissue and by using intrauterine pressure recordings in vitro and in vivo. Today, ultrasound has made it possible to study this activity with a noninvasive approach and to assess uterine contractions (UCs) in real-time movements of the uterus. Throughout the menstrual cycle, wavelike activity patterns of the reproductive organ were established. These patterns are under control of steroid hormones. Adequate UCs may provide for gamete/embryo transportation throughout the uterotubal cavities and successful embryo implantation in spontaneous and/or assisted reproduction. Inadequate UCs may produce ectopic pregnancy, miscarriages, retrograde bleeding with dysmenorrhea, and endometriosis.