Clozapine is an antipsychotic agent that has proved to be effective in treatment-resistant schizophrenia. Its use is reserved for patients unresponsive to other medication or intolerant of alternatives due to their adverse effects . It may also be prescribed for psychosis associated with Parkinson's disease where conventional treatment has failed. In treatment-resistant schizophrenia, clozapine should only be prescribed by physicians well versed in the use of clozapine therapy in psychiatric illness or by psychiatrists. In psychosis associated with Parkinson's disease, clozapine may also be prescribed by a neurologist. When treated with clozapine many schizophrenic patients can be managed in the community. Primary care physicians should therefore be familiar with the principles of monitoring clozapine therapy (frequent laboratory testing, recognition of adverse effects).