OBJECTIVE: To compare olanzapine versus haloperidol effectiveness, in terms of relapse rates in Venezuelan patients with schizophrenia. METHODS: A randomized, open label, follow-up study of 9-months after clinical stabilization or hospital discharged was conducted. The Medical Outcomes Study Form Health Survey (SF-36) and the Quality of Life Index from Mezzic & Cohen were used to evaluate the health state and quality of life. Safety parameters were collected. RESULTS: Thirty-one patients in olanzapine and 40 in haloperidol were enrolled and discontinuation rates were 65% and 68% respectively. Only one patient in haloperidol relapsed. Health status improved more with olanzapine showing statistically significant improvement in five of the eight items of the SF-36. Olanzapine was slightly superior improving quality of life. More adverse events were registered with haloperidol (p = 0.036). More extrapyramidal symptoms, akathisia and insomnia were reported with haloperidol and more weight gain with olanzapine but the differences were not significant. CONCLUSIONS: Both medications were similar preventing relapses. Health status and functionality improved more with olanzapine versus haloperidol. Safety results are consistent with the known profile of the drug. Study limitations on design and conduction of this study restrict its generalization.