We experienced a case of primary intestinal lymphangiectasia in a 20-month-old boy, which was confirmed gastrofiberscopically and histologically only after a high-fat meal before the procedure. A characteristic endoscopic finding was the appearance of tiny white dots scattered in the duodenal mucosa, which were proved dilated lymph vessels in the lamina propria on histological examination. Treatment with low-fat diet and medium chain triglycerides supplementation was satisfactory.