Amyloidosis, a systemic disease characterized by the deposition of misfolded protein, is difficult to rapidly diagnose due to its wide range of symptoms. The present study reported on a case of primary amyloidosis (AL) with involvement of the gastrointestinal tract, mesentery and omentum in a 66-year-old male presenting with recurrent diarrhoea and abdominal distension. Oesophagogastroduodenoscopy and enteroscopy revealed multiple gastric ulcers and multiple protuberant lesions in the colon. Laparotomy indicated multiple nodules in the mesentery of the small intestine. Contrast-enhanced CT revealed dilation of the small bowel with pneumatosis intestinalis and positive Congo red staining of gastric mucosa and mesentery biopsy specimens confirmed amyloid deposition. Therefore, the patient was diagnosed with AL. In this case, the clinical manifestation of mesentery amyloidosis was multiple nodules and extensive peritoneal adhesions, which, to the best of our knowledge, has not been reported by any previous study.