The aim of this study was to compare the reliability of 99Tcm-sestamibi myocardial scintigraphy for the assessment of coronary artery disease extent using two different stresses (exercise and dipyridamole) and imaging techniques (planar versus single photon emission tomography, SPET) in a patient population of 20 subjects, all also studied with coronary angiography. The agreement of exercise and dipyridamole was good for the visual uptake score (planar K=0.71, SPET K=0.64) and for abnormal segment detection (planar and SPET both K=0.76). For the recognition of the individual diseased vessel, the results of exercise and dipyridamole planar scans were equal (sensitivity 49%, specificity 90%, accuracy 63%); those of exercise and dipyridamole SPET were also similar and were both better than the related planar data (sensitivity 79% and 74%, P<0.005 and <0.02, respectively, versus planar; specificity 95% and 100%; accuracy 85 and 83%, P<0.001 and <0.02 versus planar). Both stresses and imaging techniques were less sensitive in cases of mild (50 to 70%) obstructions. In conclusion, exercise and dipyridamole appear equally effective stresses for 99Tcm-sestamibi scintigraphy; with both of them, however, SPET allows significantly better results than planar imaging and therefore should be recommended.