Several immunotherapies are under development for nicotine, cocaine and phencyclidine and a cocaine vaccine has started human trials. These therapies promise a new approach to diseases that have had limited treatment success and tremendous morbidity. Both the cocaine and nicotine addiction immunotherapies have reduced 'relapse' to drug use in animal model systems. To date, the active cocaine vaccine has few side effects and induces considerable antibody titers after active immunization in humans. Studies with the monoclonal phencyclidine immunotherapy provide intriguing evidence of sustained protection for months after single-dose administration. Other immunotherapy may include treatment of drug overdose, prevention of brain or cardiac toxicity and protection of a fetus during pregnancy in a drug abuser.