We report the clinical observation of a 58-year old patient who presented with upper abdominal pain and a small ecchymosis located in the umbilical area. Personal history of the patient revealed ischemic heart disease and chronic atrial fibrillation. He was under treatment with oral anticoagulants (coumarins). The clinical data and especially the imaging investigations led to a diagnosis of gastric wall hematoma, possibly occurring post-traumatically in a patient under anticoagulant treatment. A conservative therapeutic approach was adopted and ultrasound surveillance. After 6 months the gastric parietal collection manifested complete resorption, spontaneously. In relation to the case presentation, we also discuss some issues on the frequency, diagnosis and therapeutic attitude in this rare complication of anticoagulant therapy.