The results from a field study on autochthonous visceral leishmaniasis on the island of São Luís are presented. This study started in 2004 and finished in 2006 and had the aim of ascertaining the determinant epidemiological and clinical characteristics of this endemic disease. Two hundred ninety nine autochthonous cases were analyzed, of which 83.6% were children younger than 9 years old and 54.1% were male. The disease occurred in all months of the year, with a peak in June. The coefficient of incidence decreased from 46.1 to 35.2 cases per 100,000 inhabitants over the years studied. The diagnosis was confirmed by laboratory tests in 93.3% of the cases. The treatment of choice was based on N-methylglucamine, with a cure rate of 96.1%. The mean lethality rate was 3.7%. Because of the absence of systematic control actions, the authors propose the creation of a specific program to be developed by the municipalities under the coordination of the State Department of Health.