Stress is commonly associated with drug craving and relapse in substance-dependent individuals. Several studies indicate that hypothalamic neuropeptides may mediate behavioral response to stress. For example, preclinical and clinical investigations have indicated that the neuropeptide oxytocin exerts anxiolytic effects in stress paradigms. Several studies have indicated that oxytocin promotes trust, social bonding, and calmness; however, little is known about the potential anxiolytic affects of oxytocin in marijuana-dependent individuals. A preclinical study investigating the effects and mechanism of lithium on cannabinoid withdrawal in rats had positive findings, with increasing oxytocin levels hypothesized to moderate this effect (Cui et al, 2001). Given the anxiolytic nature of oxytocin, it may have a therapeutic role in ameliorating the negative affect commonly observed prior to relapse in marijuana-dependent individuals, as well as the anxiety associated with marijuana withdrawal. This pilot protocol will provide important preliminary data on the effect of oxytocin on stress in marijuana-dependent individuals.