Introduction: Computed tomography (CT) is an important imaging modality for investigating the cause of abdominal symptoms. Bowel wall thickening (BWT) is a common, non-specific finding on abdominal CT and is caused by a variety of underlying etiologies. This finding frequently leads to further invasive investigations including colonoscopy; however, its relevance to the clinical presentation is often unclear. Our aim was to determine the causes and relevance of bowel wall thickening on CT abdomen at an Australian metropolitan hospital and to review its significance when the CT ordered is appropriate or inappropriate for the clinical indication. Methods: We performed a retrospective review of all consecutive abdominal CTs between February and May 2015, with findings of BWT on the formal report. The CT request details, formal report, medical records, indication for ordering the CT and the appropriateness of this indication, as well as clinical course and subsequent colonoscopy findings, were reviewed for each patient. The American College of Radiology Practice Parameter for the Performance of CT of the Abdomen and Pelvis 2014 was used to determine the appropriateness of CT ordering. Results: Of the 175 abdominal CTs identified, the final causes of bowel wall thickening were diverticulitis (28%), infection (24.6%), reactive to extra-colonic inflammation (10.9%), flare of known inflammatory bowel disease (6.9%), bowel obstruction (5.7%), new cancer (5.7%), and ischaemic colitis (0.6%). None of the patients had a new diagnosis of inflammatory bowel disease. Overall, 50/175 (28.6%) patients underwent subsequent colonoscopy and of these, 41/50 (82%) were either normal or showed uncomplicated diverticular disease only. 10/175 (5.7%) CTs ordered were deemed inappropriate for the indication given. Of these, 3/10 (30%) underwent subsequent colonoscopy as a result, and none of these patients had any significant pathology identified. Conclusion: BWT is a highly non-specific finding on CT abdomen and requires careful correlation with the clinical scenario for accurate interpretation. Although inflammatory bowel disease and cancer are feared to be the underlying etiology in many cases, these appear to be relatively rare causes compared to infection and diverticulitis. BWT was more likely to be significant if the CT was ordered appropriately and therefore, inappropriate ordering should be minimized to avoid unnecessary cost, concern and further investigation.