Preterm birth accounts for the majority of neonatal morbidity and mortality not associated with congenital anomalies. Its incidence has remained relatively unchanged over the past 15 to 20 years. Tocolytic therapy has been shown to be ineffective in the prevention of preterm labor but can delay delivery by approximately 48 hours. Four major drug groups are currently available. The article reviews each drug group, including mechanism of action, pharmacology, side effects, efficacy, and nursing implications.