Preterm birth is the major cause of neonatal mortality and morbidity in the developed world. The perfect tocolytic that is uniformly effective with complete fetomaternal safety does not exist. Tocolytic agents differ in cost, utero-specificity, safety, efficacy and whether they are licensed for use. The main three agents that are used worldwide are beta-agonists, Ca(2+) channel blockers and vasopressin/oxytocin receptor antagonists. beta-Agonists are gradually being phased out of use and are being replaced by either nifedipine or atosiban. The evidence base for atosiban is strong but the evidence is of poor quality for nifedipine. The balance of evidence indicates that atosiban is as effective as nifedipine and more effective than beta-agonists and is significantly safer than both. Atosiban was developed specifically to treat preterm labor, so the cost is higher than nifedipine or ritodrine. However, the cost of a course of atosiban (approximately 200 pounds) should not only be considered in comparison with other tocolytic agents but to other medical budgets (e.g., oncology, fertility, cardiology and psychiatry) and to the huge healthcare costs associated with the morbidity and mortality caused by preterm birth. Atosiban is a new advance in the management of spontaneous preterm labor.