A 2-month-old filly was evaluated for severe colic. Ultrasound, abdominocentesis and physical examination findings prompted an abdominal exploratory surgery. Perforation of the stomach was discovered during the surgery. The filly was humanely subjected to euthanasia under anaesthesia and post mortem examination was performed. In addition to gastric and duodenal ulceration, a thickened, black area of the proximal oesophagus was discovered. Histopathology of the lesion revealed primary malignant melanoma. Although rare, primary melanoma can occur in noncutaneous locations.