The use of cardiovascular imaging is growing inexorably and concerns have been expressed about its cost and radiation safety. In this study, the relative environmental impact of MRI, single photon emission tomography and cardiac ultrasound (echo) for the diagnosis of coronary artery disease were examined. The results emphasise that echo causes the least environmental impact at each stage of its life cycle. The effect of one echo on human health, ecosystem effects and resource use was of the order of 1-20% of those of the alternative methods. Although there are circumstances in which one imaging modality is preferred on clinical grounds, when everything else is equal, these results support the selection of echocardiography as the preferred test on environmental grounds.