OBJECTIVES: To assess the suitability of electron beam computed tomography (EBT) in evaluating and subsequently managing cardiac masses suspected as a result of examination by transthoracic and transoesophageal cross sectional echocardiography. DESIGN AND PATIENTS: In 76 consecutive patients with suspected cardiac masses, the impact of the EBT examination was analysed by reviewing whether EBT examination altered management by confirming or excluding a mass, whether EBT imaging substantially contributed to decision-making, and lastly whether EBT influenced the decision to operate on the patient. RESULTS: EBT modified the diagnosis or confirmed results which had been questionable with cross sectional echocardiography in 53 cases (70%): these cases included those with anatomical features such as dense calcifications or fatty structures (n = 20), lipomatous lesions (n = 5), equivocal thrombi (n = 5), pericardial masses (n = 5), or hydatid cysts (n = 2). EBT gave information over and above cross sectional echocardiography in all patients with malignant tumours (n = 16) by providing a better delineation of the relation between intracavity masses and normal structures, including the mural site of tumour attachment and tumour extension to the great vessels and the adjacent extracardiac mediastinal structures. EBT provided no additional information over cross sectional echocardiography in the remaining patients (n = 23), particularly in those with myxomas (n = 11) or small valvar lesions (n = 6). EBT only confirmed that the lesion was well demarcated, limited in extent, or not associated with a mass. CONCLUSIONS: EBT has considerable potential for clinical management and surgical planning and may help clinicians to decide against surgery, particularly in patients with unresectable tumours.