NoR~labour is charaeterized by a co-ordinated pattern of uterine con-"tractions and complete dilatation of the cervix within a reasonabl~ length of time. Caldeyro and Alvarez (1) in their study of normal labour found that during a contraction the intra-uterine pressure ranged between 80 and 50 ram, of mercury. According to them, the intxa-uterine pressure between contractions, i.e. the resting or basal tone of the uterus, was usually 8 to 12 mm of mercury. Their uterine tracings and recordings :showed that a normal contraction pattern started in the fundus and was of greater intensity in that region as compared to the lower segment. Thus the characteristic of normal labour, as demonstrated by these workers, is active participation of all parts of the uterus with strong synchronized contractions starting in the fundal region.In contrast to this, primary uterine inertia is characterized by a prolonged and painful first stage of labour with incomplete dilatation of the cervix a~-ter 24 to 48 hours of ineffectual incoordmate contractions. Clin'ically, this state is apparent in patients who show signs of emotional tension and fear. In these eases, both the intensity of contractions and the resting tone of the uterus between contractions, may show a great deal of variation. Moreover, the contraction waves of fundal origin, and the normal gr~chent of activilrz from the upper to the lower segment are lackitLg. Instead, an abnormally wea_c or strong anti-peristaltic contraction pattern persists. These abnormal contractions are associated with slow and painful dilatation of the cervix. Labour becomes virtually arrested after a "trying first stage and many of the patients become hysterical, uncooperative and dfltlcult to manage.MacRae (2) defined primary uterine inertaa as a frst stage of labour, which, in the absence of cephalo-pelvic chspIoportion has lasted 48 hours or more. He recognized six types. In his experience, the atonie uterus and the hffpertonie uterus with cervical achalasla were the most common.. He defined cervical achalasia as non-relaxation of the cervix despite continued severe contractions of the uterus. In his series, the condition was encountered in 8.2 percent of obstetrical cases and was more common in the emotionally hyperactive primipara. He stressed the high incidence of maternal morbidity and the high foetal loss. Asphyxm and intra-uterine infection were responsible for the foetal wastage in these cases.1effcoate (8) considered the hypertonic type of inertia to be the more common and alluded to the functional aspect of this disturbance.