The case reported concerns a child with chronic intestinal pseudo-obstruction (CIPO) whose digestive manifestations (intestinal adynamia and distension) were present from the age of 6 months and lasted, despite medical and surgical treatments until 4 years of age, when death occurred. The multiple samplings showed important inflammatory reactions centred on the muscular layers of the small intestine, together with degenerative lesions of the muscular fibres, progressively leading to fibrosis and atrophy of the intestinal wall with secondary and final impairment of the myenteric plexuses. The diagnosis of myositis of the small intestine is extremely rare. It is not part of the usual causes of intestinal adynamia and CIPO, which were reviewed. Hollow visceral myopathy and systemic sclerosis of the GI tract were more especially discussed. For lack of etiopathogenic convincing data and of similar observation in the literature, this case may be temporarily considered as an idiopathic myositis of the small intestine, a potentially new cause of CIPO.