Clonidine's actions and efficacy in mental disorders are reviewed and examined. Its efficacy in suppressing acute opiate withdrawal symptoms and its role in preparing the opiate-dependent patient for transition from opiate agonist to naltrexone therapy are well documented. Studies also indicate clonidine's value in alcohol and tobacco withdrawal syndromes. Of special interest is evidence which suggests that clonidine can reduce the duration and cost of the withdrawal process. Also discussed is clonidine's utility for mania, anxiety and panic disorders, schizophrenia, and the symptoms of tardive dyskinesia. Although further documentation of its efficacy for these disorders is required, clonidine's efficacy as an antimanic agent and treatment for tardive dyskinesia is particularly exciting and worthy of further study.