The present study aimed to evaluate the anthelmintic effect of Carapa guianensis (andiroba) on gastrointestinal nematodes in sheep naturally infected in the Western Amazon. Toxicity tests with Artemia salina identified that the ethanolic extracts of the root and stem of andiroba showed an LC50% equal to 530 μg ml-1 and 170 μg ml-1, respectively. As concentrations 1.06mg / ml (andiroba root) and 0.34mg ml-1 (andiroba stem) were tested in groups of crossbred sheep, eaten from four to six months and weighing approximately 19.9 kg naturally infected by gastrintestinal nematodes. In addition, there will be a total of two treated groups and two control groups (negative and positive - 7.5% closantel). Foram extracts applied orally in a single treatment days 1,2,3,4,15,16,17,18. Or treatment lasted 30 days. Samples of fezes and blood foram collected at intervals of seven and 15 days respectively to assess the parasitic and hematological profile. The results showed a reduction in parasitic load of 86% and 59%, respectively, for the root and stem of andiroba in egg count per gram of feces, while in the group treated with closantel 7.5% the reduction was 66%. Regarding the number of third stage larvae recovered from sheep after treatment, it was observed that the groups treated with andiroba root and stem differed (p < 0.05) from the control group, with a reduction in the percentage of larvae from 70 and 55%, respectively. The phytochemical tests in the present study revealed the presence of bioactive metabolites that may be responsible for the anthelmintic activity. As for the hematocrit, there was no statistical difference in its values in the groups treated with andiroba root and stem, that is, in some way there was interference on the adult forms of the nematodes that compromised the hematophagism. Therefore, the extract of Carapa guianensis has anthelmintic potential, being a good alternative in the control of sheep endoparasitosis.