The long-term use of NSAIDs (non-steroidal anti-inflammatory drugs) is the most common cause of peptic ulcer diseases1 that occurs from an imbalance between the defensive factors of the gastric mucosa and the harmful factors. Although there are several therapeutic efficacies (e.g omeprazole, lansoprazole, ranitidine, antiacids), adverse effects and drug interactions have been shown to be associated with these drugs2. Hence, our study focused on new potential anti-ulcer molecules from medicinal plants with definite biological functions and, possibly, fewer side effects. In this context, we are investigating the gastroprotective effect of seeds of Persea americana (Mill.) commonly known as ‘avocado’. Although their leaves and fruit pulp are used in traditional medicine for the treatment of different diseases (hypertension, pain, inflammation, gastric ulcer) mainly by antioxidative effects, little is known about avocado seed.3 The aim was evaluate the capacity of seeds from Persea americana Mill. to reduce production of reactive oxygen species (ROS) and to decrease the gastric lesions induced by indomethacin, a classic NSAID. The crude extract was obtained by turbolysis with 70% alcohol, rotaevaporated, fractionated with ethyl acetate and dried at room temperature. For the study male adults Swiss mice (30-40g) subdivided into five experimental groups CEUA (404-2016) in acute treatment: Control, Indomethacin, Lansoprazole, P125, P250 mg/kg, and sacrificed after 6 hours of Indomethacin exposure (40mg/kg). Blood was collected for analysis of oxidative stress, withdrawal of stomach for lesion and gastric pH analyzes. Preliminary studies of macroscopic stomach quantification indicated that the seed reduced the lesion area induced by NSAIDs in approximately 4-fold. The P250 group (1.052 ± 0.2741%) presented similar protective results when compared to Lansoprazole (0.6600 ± 0.2484%), and significance when compared to Indomethacin (3,656 ± 0,8475%). These preliminary data suggest that Persea americana Mill. can be used as a new therapeutic strategy to prevent gastric lesions induced by NSAIDs, probably because of their antioxidant properties, which will be confirmed in subsequent experiments.