introduction: azadirachta indica a. juss, known as neem tree, has various applications in agriculture, veterinary medicine and health care, thus it is a relevant vegetable species due to its antimicrobial, antiparasitic and immunostimulating properties. objective: to detect any signal of toxicity after daily oral administration of decoction for 28 days. methods: a repeated dose toxicity assay using a a. indica decoction at a dose of 1000 mg/kg, orally administered to sprague dawley rats for 28 days. clinical signs and body weight of the study animals were evaluated together with hamatological, blood chemistry, anatomopathological and histopathological analyses. results: this decoction brought about neither significant change in the body weight nor clinical signs indicating toxicity. there were not altered hematological and biochemical indicators that may be attributed to the substance under testing. the anatomopathological results did not show any alteration upon systems, organs and tissues. conclusions: the study did not reveal toxic effects in the animal model that might be connected with the repeated oral administration of a. indica decoction under the study conditions.