Despite predictions that 201Tl imaging would be completely supplanted by the new 99mTc perfusion agents, thallium perfusion imaging is alive and well. In fact, in the past year, important new information on thallium imaging continued to emerge. Among the new data, the reinjection of a "booster" dose of 201Tl after the redistribution images has been heralded as a breakthrough that would equal positron-emission tomography in the prediction of myocardial viability. Pharmacologic coronary vasodilation has been increasingly popular, especially since the approval of intravenous dipyridamole by the Food and Drug Administration and in view of recent studies showing that adenosine is a very attractive alternative to dipyridamole in patients who cannot exercise. Beyond the undisputed diagnostic value of dipyridamole-thallium imaging, data on risk stratification continue to accumulate for patients receiving peripheral vascular surgeries as well as for those recovering from a myocardial infarction. The advent of single-photon emission CT in combination with 201Tl imaging allows improved quantification of jeopardized myocardium. This technique has now been used increasingly to complement the information obtained from coronary angiography by the determination of the functional significance of known coronary stenoses. Recent studies have shown marked heterogeneity in the extent of jeopardized myocardium in patients with coronary artery disease. Equally important have been recent reports on the high prevalence of silent ischemia in patients undergoing 201Tl exercise scintigraphy. Technical progress has also enhanced the diagnostic capability of 201Tl imaging, allowing sharper identification of perfusion defects and quantification of reversible myocardial ischemia precipitated by exertion. Finally, one of the most exciting areas of research in thallium scintigraphy is its established prognostic value in patients with stable angina or those recovering from a myocardial infarction. Recently, these prognostic data have also been extended to patients with unstable angina or those receiving thrombolytic therapy.