Abstract Background Polyarteritis nodosa is a disease that presents with necrotizing vasculitis in small and medium-sized arteries. It may occur in various organs, but approximately half of cases have gastrointestinal involvement. Prognosis is not favorable once organ dysfunction begins as evidenced by gastrointestinal symptoms; thus, treatment with steroids should be promptly initiated. We report the case of a patient who presented with necrosis of the small intestine, which was pathologically diagnosed as polyarteritis nodosa and treated successfully with steroids. Case presentation An 18-year-old Japanese woman reported a sudden onset of abdominal pain and vomiting that led her to visit our emergency department, where she was evaluated b...