A 41-year-old woman in November 2002 underwent a gastric bypass by the Capella technique for morbid obesity. Almost 1 year after the surgery, she developed severe vomiting. Radiological studies confirmed a severe stenosis of the gastrojejunal anastomosis. Two pneumatic dilatations of the stenosis failed. In February 2004, she underwent resection of the stenotic anastomosis. Histology showed an intact mucosa and beneath it an abscess filled with numerous filamentous microorganisms, with typical features of Actinomyces. With the diagnosis of gastric actinomycosis, she received a postoperative course of antibiotherapy with imipenem and was discharged after an uneventful recovery. Gastric actinomycosis is a rare infection, of which only 19 additional cases have been reported in the literature. To our knowledge, this is the first case to affect a patient following batriatric surgery. The reported cases of this entity are reviewed, and the diagnostic criteria that could avoid surgery in these cases are discussed.