Eosinophilic gastroenteritis is a rare disease of unknown aetiology characterized by eosinophilic infiltration of the gastrointestinal wall and increased peripheral blood eosinophilia. The frequent finding of concomitant extradigestive involvement calls for differential diagnosis to distinguish some multisystemic pathologies, such as connective tissue disease. We recently treated a young woman affected by eosinophilic infiltration of the small and large intestine which spread to other organs. Tests ruled out allergic or parasitic aetiopathogenesis of the disease. The clinical, biological and evolutive findings suggest that eosinophilic gastroenteritis may evolve into idiopathic hypereosinophilic syndrome.