An 8-year-11-month-old girl had protein-losing enteropathy associated with arsenic poisoning; to our knowledge, this is the first such case to be reported. A total dose of about 31 mg of arsenic trioxide was given orally during a two-month period for verrucae planae juveniles of the dorsal surface of the hands. About four weeks later edema, especially of the legs and eyelids, was noted. Jejunal biopsy with a Crosby's capsule revealed an abnormal dilated villus and mild atrophy of the submucosa. The treatment with dimercaprol resulted in improvement of both hypoproteinemia and edema.