The neoplastic change in patients with Crohn's disease is usually seen in the form of adenocarcinoma. Primary gastrointestinal lymphoma complicating chronic inflammatory bowel diseases is thought to be uncommon. This report describes a case of gastrointestinal lymphoma in a 12-year-old boy with Crohn's disease of one-year duration that initially manifested as an abdominal mass. Although Crohn's disease may present as a palpable abdominal mass, changing symptomatology should always warrant consideration of developing lymphoma complicating inflammatory bowel diseases. It is our hope that this case report gives the clinician an insight into the possibility of lymphoma development, even in the early course of the disease, and stresses the importance of obtaining a reliable histological diagnosis whenever possible.