Crohn’s disease is a chronic inflammatory bowel disease, involving gastrointestinal tract and extra-intestinal organs. IgA nephropathy is a rare extra-intestinal manifestation of Crohn’s disease. We describe a case of 21-year old Korean man who was diagnosed with Crohn’s disease 5 years after IgA nephropathy was suspected. At the age of 16, he had gross hematuria and 2 years after he was diagnosed with IgA nephropathy. Three years later, he complained of abdominal pain and diarrhea. He was diagnosed with Crohn’s disease by colonoscopy and histologic exams. There has been increasing evidences of common pathophysiology between the two diseases.

• 고석영(국립경찰병원 내과) | Seokyoung Koh (Department of Internal Medicine Seoul National Police Hospital, Seoul, Korea)
• 김재연(국립경찰병원 내과) | Jaeyeon Kim (Department of Internal Medicine Seoul National Police Hospital, Seoul, Korea) Corresponding author
• 서승오(국립경찰병원 내과) | Seong O Suh (Department of Internal Medicine Seoul National Police Hospital, Seoul, Korea)
• 박지현(국립경찰병원 내과) | Jihyeon Park (Department of Internal Medicine Seoul National Police Hospital, Seoul, Korea)
• 박용욱(국립경찰병원 병리과) | Yong Wook Park (Department of Pathology, Seoul National Police Hospital, Seoul, Korea)