Cannabis has been reported to produce acute psychiatric reactions, among these panic anxiety and derealization, which are self-limited. We report on three patients who experienced an initial panic attack during cannabis intake. Anxiety attacks reoccurred after the cessation of intake. Two of these patients had a current depressive disorder, one of them had a single Grand Mal seizure before the onset. We suggest that cannabis may trigger the emergence of recurrent panic attacks and uncover latent panic disorders in vulnerable persons.