The clinical course of diverticular disease in immunosuppressed patients is widely believed to be more severe than in the general population. In this study we systematically reviewed the literature regarding the epidemiology and clinical course of diverticulitis in immunosuppressed patients. Our goal was to develop recommendations regarding the care of this group of patients. Using PubMed and Web of Knowledge we systematically reviewed all studies published between 1970 and 2009 that analyzed the epidemiology, clinical manifestation, or outcomes of treatment of diverticulitis in immunosuppressed patients. Keywords of "transplantation," "corticosteroid," "HIV," "AIDS," and "chemotherapy" were used. Twenty-five studies met our inclusion criteria. All of these studies focused on the impact of diverticulitis in patients with transplants or on chronic corticosteroid therapy. The reported incidence of acute diverticulitis in these patients was approximately 1% (variable follow-up periods). Among patients with known diverticular disease the incidence was 8%. Mortality from acute diverticulitis in these patients was 23% when treated surgically and 56% when treated medically. Overall mortality was 25%. Our study summarizes evidence that patients with transplants or patients on chronic corticosteroid therapy 1) have a rate of acute diverticulitis that is higher than the baseline population and 2) a mortality rate with acute diverticulitis that is high. Further research is needed to define whether these risks constitute a mandate for screening and prophylactic sigmoid colectomy.