The aim of the study was to test the clinical value of attenuation-corrected (AC) thallium-201 single-photon emission tomography using a moving gadolinium-153 line source in a group of patients in whom coronary angiography was planned because of clinically suspected coronary artery disease (CAD). Furthermore, we wanted to test the impact of AC on assessment of the extent and severity of perfusion abnormalities. A total of 107 patients planned to undergo coronary angiography were included in the study. In each patient, AC and NC (non-corrected) 201Tl SPET was performed. AC and NC images were evaluated visually as well as by a 31-segment semiquantitative analysis and the findings were correlated with angiographic results. Patients were assigned to two groups: group A with angina and no previous cardiac infarction or intervention and group B with known CAD because of previous myocardial infarction or intervention. With visual analysis, NC revealed a sensitivity of 88.9% in group A and 74.3% in group B, compared to 94.4% in group A and 94.3% in group B with AC. Specificity for NC was calculated to be 68.7% for group A and 91.3% for group B. AC demonstrated significantly higher specificity of 83.9% and 100% respectively. This effect was particularly demonstrated for males and bicycle workload. The extent and severity of perfusion abnormalities were significantly influenced by the use of AC, in that significantly fewer abnormal and less severely abnormal segments were demonstrated in the segmental analysis as compared to NC; this was especially true for the vascular territory of the left anterior descending artery and the right coronary artery. It is concluded that AC with a moving line source is feasible in patients with all degrees of probability of CAD. AC has a significant impact on the assessment of the severity and extent of myocardial ischaemia, especially in the posterior and septal wall.