The objective of this study was to describe a case of salmonellosis in an Amazonian manatee (Trichechus inunguis). The animal was rescued from a tributary of the Capim River, in the municipality of Goianésia do Pará, Pará, Brazil, kept in a pool, and died approximately five months after being rescued. The main changes observed at necropsy were that the cecum and colon had serosal hyperemia, wall edema, thickened mucosa with ulcerated areas and covered by a thin layer of fibrin, and a yellowish liquid content. Histologically, there was moderate multifocal fibrinonecrotic typhlocolitis associated with intense bacterial colonization. Salmonella enterica subsp. enterica (rough) was isolated in cecum and colon fragments. This is the first report of salmonellosis in an Amazonian manatee.