Although modern intensive care of the premature newborn has improved the infant`s chances of healthy survival, prematurity is still the major cause of neonatal morbidity and mortality. Recognition of these problems has led to effort aimed at either prevention of pret erm labor or inhibition of the process once it has begun. Adrenergic betamimetic compounds are known to be potent inhibitors suppressing the intensity of uterine contractions. However, because these compounds also affect the cardiovascular system, causing marked hypotension and tachycardia,their clinical usefulness has been limited. A double-blind placebo-controlled study with Ritodrine had been performed in 38 patients in premature labor. All patients were treated according to the fixed dosage scheme consisting of an intravenous infusion followed by oral tablets for total seven days. The results of this study were as follows: 1.There were no statistically singificant differences in clinical characteristics such as- maternal age,parity,gestational weeks,cervical dilatation,initial maternal heart rate and blood pressure. 2.Labor was successfully postponed for more than 24 hours in 17 cases(89.5%) and one week or more in 14 cases (73.7%) of 19 cases with intact membranes,who were treated with Ritodrine, while in the placebo group these were seen in 6 cases(50.0%) and 4 cases(33.3%) of 12 cases, respectively. The difference between the two groups is statistically significant. 3.The mean gain days were 29.2 in treated group with intact membrans and 10.3 in placebo with intact membranes. The difference between the two groups is statistically significant. 4.The maximal maternal heart rate was significantly elevated during Ritodrine infusion. But the maximal systolic and minimal diastolic blood pressure, and maximal fetal heart rate did not change significantly. 5.There was no statistically signicant difference between the two groups in the 1 and 5 minute Apgar scores of the newborn.