Novel sites of oxytocin receptor expression have recently been detected, including breast cancer cells, bone cells, myoblasts, cardiomyocytes and endothelial cells. These discoveries have greatly expanded the possible spectrum of oxytocin action beyond its classic role as an inducer of uterine contractions and milk ejection. Additional advances in the understanding of oxytocin receptor structure-function relationships, receptor trafficking and novel receptor-linked signaling cascades have made this receptor an attractive model for the study of G-protein-linked receptor function. Finally, the tocolytic efficiency of the oxytocin receptor antagonist atosiban, recently approved for clinical use in Europe, has opened new avenues for the prevention and treatment of preterm labor.