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The mainstay of treatment for schizophrenia is the antipsychotic group of drugs. Usually oral forms are preferred but problems with treatment adherence are common. Depot antipsychotics provide a reliable drug delivery to patients, whose adherence with oral medication is suboptimal. Haloperidol decanoate (HD) is one of the depot drugs available in clinical practice. The monthly-administered depot formulation of haloperidol has several clinical and practical advantages over oral haloperidol: better compliance and a more predictable absorption, more controlled plasma concentrations, fewer extrapyramidal side effects. The major side effect of antipsychotic therapy, including HD, is the production of extrapyramidal symptoms. The incidence and intensity of symptoms may be less with HD than other antipsychotic drugs, especially when the dose is not too high. The concomitant use of anti-parkinsonian drugs also tends to be less with the depot preparation. Cases. Nine hospitalized chronic psychotic patients were treated with HD using two different dosage schedules for loading-dose, which were calculated from the previously prescribed daily oral dose of haloperidol multiplied by a factor 20. HD given in divided doses of 100 mg 4 times in every 5 days in 5 patients and 200 mg 2 times in every 7 days in four patients until the full amount was administered in first month. This HD dosing pattern was repeated during the second month, but at a lower dose (25% less) to compensate for drug accumulation. Anti-parkinsonian therapy prescribed during the first month of loading-dose. Extrapyramidal side effects were reported in two patients. The other seven patients were successfully withdrawn from anti-parkinsonian therapy without experiencing an enhancement of extrapyramidal side effects at the end of loading-dose. Usage of two different dosage schedules did not effect on side-effect profile. There were no significant haematological or biochemical changes. No local or systemic side effects were observed during the trial. Patients, 6 of 9 were unstable with risperidone and zuclopenthixol long-acting injectable preparations in previous medications, were well stabilized on their optimal dose schedule. Stabilization or slight improvement was observed for symptoms of psychosis. Six of 9 patients continued treatment with HD 200 mg monthly with any extrapyramidal side effect and with any anti-parkinsonian therapy prescription. Treatment guidelines for schizophrenia recommend that clinicians strongly consider depot medication for patients who may be non-compliance to antipsychotic treatment regimens. Non-compliance to antipsychotic treatment in schizophrenic patients leads to relapse and re-hospitalization. HD offers a useful alternative in the treatment of psychoses to orally administered haloperidol or to other depot antipsychotic drugs.