Recent studies have established the reliability, validity and time course of the cannabis withdrawal syndrome characterized by symptoms of anxiety, irritability, negative mood, physical symptoms and decreased appetite. This study will investigate the effects of combined treatment of Escitalopram with cognitive-behavior therapy in alleviating the symptoms of the marijuana withdrawal syndrome in regular chronic users of marijuana. 40 patients will be blindly randomized to either active or placebo escitalopram 10mg/day, for 12 weeks followed bt 12 weeks of follow-up.