Collagenous sprue is a rare enteropathy affecting the small intestinal mucosa and can resemble and coincide with coeliac disease or collagenous colitis. To our knowledge, less than 175 cases of collagenous sprue have been described. Both clinicians and pathologists should be aware of the condition in order to adequately target their investigations and treatment. This is a case report of severe collagenous sprue in a 78-year-old male resulting in severe diarrhoea, weight loss, malnutrition and acute kidney failure. The disorder improved on a lactose and gluten-free diet, loperamide and corticosteroids.