The aims of this review are to precise the incidence of non-Hodgkin's lymphoma and Hodgkin's disease in inflammatory bowel disease and to assess the relationship between immunosuppressive therapy and lymphoma in inflammatory bowel disease. Population-based data show that incidence of lymphoma is not increased in patients with Crohn's disease or ulcerative colitis. There is an increased incidence of non-Hodgkin's lymphoma in inflammatory bowel disease patients on immunosuppressive therapy but overall risk is low in all cohort studies. Relationship between immunosuppression and lymphoma in inflammatory bowel disease is confirmed by frequency of cerebral lymphoma and association with Epstein-Barr virus.