INTRODUCTION: Diverticula (mucosal outpouching through the wall of the colon) affect over 5% of adults aged 40 years and older, but only 10-25% of affected people will develop symptoms such as lower abdominal pain. Recurrent symptoms are common, and 5% of people with diverticula eventually develop complications such as perforation, obstruction, haemorrhage, fistulae, or abscesses. METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of: treatments for uncomplicated diverticular disease; treatments to prevent complications; and treatments for acute diverticulitis? We searched: Medline, Embase, The Cochrane Library and other important databases up to July 2006 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). RESULTS: We found 13 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. CONCLUSIONS: In this systematic review we present information relating to the effectiveness and safety of the following interventions: antispasmodics, bran, elective surgery, increasing fibre intake, ispaghula husk, lactulose, medical treatment, mesalazine, methylcellulose, rifaximin, surgery.