This is the first reported case of rectal vascular ectasia in association with gastric antral vascular ectasia (watermelon stomach). The patient, a 39-year-old woman with systemic sclerosis, reported chronic gastrointestinal blood loss and iron deficiency anemia. She had aperistalsis of the distal esophagus, decreased lower esophageal sphincter pressure leading to severe gastroesophageal reflux, and dysmotility of the small intestine. Diagnosis was made by endoscopic appearance of visible linear watermelon-like vascular stripes in the gastric antrum and rectum. Histology confirmed the vascular nature of this disorder, showing dilated and thrombosed capillaries in the lamina propria. Gastric biopsy showed associated fibromuscular hyperplasia in the lamina propria. However, the colonic biopsy showed only focal hyalinization in the lamina propria. The patient was successfully treated using endoscopic bipolar electrocautery. Watermelon stomach has previously been described in association with systemic sclerosis. Based on the histopathologic similarity between rectal vascular ectasia, gastric antral vascular ectasia, and systemic sclerosis, we suggest that the rectal vascular lesion may represent a component of the gastrointestinal manifestations of systemic sclerosis.