Alcohol dependence is a major health problem worldwide and recently in Israel and it has major health care costs. Cannabis dependence is also a major health issue and many cannabis users find it difficult to quit. Similar to dependence on heavy drugs, alcohol and cannabis-dependent patients find it difficult to quit drinking and smoking cannabis and they relapse to drinking alcohol and using cannabis during treatment. Craving for alcohol and cannabis and withdrawal during detoxification are major factors for relapse to drinking and using cannabis. The cue-exposure and priming paradigms have been used in order to induce craving for alcohol and cannabis in the laboratory. Several studies have delineated the brain mechanisms responsible for cue-induced craving for alcohol using functional Magnetic Resonance Imaging (fMRI), a method that can be useful in monitoring progress of treatment. A proven useful medication for treatment of alcohol dependence is the opiate antagonist naltrexone commonly used for treatment of opiate dependence. We have found that cannabis-dependent patients in treatment for cannabis dependence who also were heavy users of alcohol have dropped early from treatment.