The hormone oxytocin is known for its widespread effects on social and reproductive processes, and recent data from intranasal administration in humans has produced hope for its use as a therapeutic in autism, schizophrenia, and other disorders. However, this leap to human use is happening without previous animal studies of long-term oxytocin administration, and without knowledge of the neurobiological mechanisms involved in the behavioral findings. A new study indicates that the promising short-term effects often observed after a single dose of oxytocin may not translate to positive effects after long-term administration.