OBJECTIVES: To determine the effect of including the costs and risks of medical negligence claims on the results of a cost-utility model of diagnostic strategies for patients with chest pain presenting at the Emergency Room. Coronary computed tomography (CT) has been proposed as an initial screening technique for patients at low risk of coronary artery disease, because it may allow earlier discharge and cost savings compared with stress-based tests such as exercise single-photon emitting computed tomography (SPECT) or exercise echocardiography (ExE). METHODS: A decision-analytic model was designed to calculate the expected costs and health outcomes at 12 months for patients at low risk of coronary artery disease presenting at the Emergency Room with chest pain.  Published data was used to predict the accuracies of the diagnostic tests. Costs were calculated from the perspective of the Australian health system, and a rate (30%) and cost of litigation ($160,000) was included for false negative diagnoses that incurred an event within the time frame. RESULTS: ExE was the least costly strategy in the base case analysis. The results are sensitive to changes in the cost and likelihood of litigation, because these costs are high relative to the other costs in the model. At a 30% claim rate, if the expected payout for litigation is