The development of "selective" drugs targeting oxytocin/vasopressin receptors has enormously progressed since the original synthesis of oxytocin more than 50 years ago. However, several factors still hamper the availability of a rich and complete range of selective agonists and antagonists acting at the different oxytocin/vasopressin receptor subtypes, making the use of these drugs still a daunting task. In this paper we will briefly review the major problems encountered when dealing with oxytocin/vasopressin selective ligands, proving few rules for their correct pharmacological use, in order to avoid common pitfalls. Finally, we will glimpse at new challenges, such us the discovery of coupling selective ligands, which foster the search for new classes of selective compounds.