BACKGROUND Myocardial perfusion single-photon emission computed tomography (SPECT) is one of the basic tools used for the purpose of diagnosis of coronary artery disease (CAD), prognosis of its unfavourable consequences, and evaluation of therapy effectiveness. However, its efficacy is compromised by a relatively low specificity of detection of perfusion defects, which is attributed to attenuation of gamma rays inside the patient's body, causing artefacts erroneously taken for perfusion defects. It is expected that attenuation correction (AC) could eliminate such artefacts. OBJECTIVE To evaluate whether visual, semi-quantitative analysis of attenuation-corrected myocardial perfusion imaging provides an advantage over a non-corrected study. METHODS A retrospective study applying AC was performed in 107 patients who had coronary angiography within three months. Patients underwent a stress/rest Tc-99m methoxyisobutylisonitrile (MIBI, POLATOM) double day SPECT/CT myocardial perfusion imaging. Images were analysed by two experienced nuclear medicine specialists (a consensus) applying a visual semiquantitative method. Coronary angiography findings were used as a reference for the analysis of diagnostic performance of myocardial perfusion study protocols. RESULTS AC increased the specificity of detection of CAD in the whole group of patients from 63% to 86% (p = 0.0005), with a slight reduction in sensitivity (from 83% to 79%). The improved specificity was also noted in subgroups of male and female patients. Accuracy in the whole group of patients increased from 71% to 83% (p = 0.01). AC improved the specificity and accuracy of the method in the detection of perfusion defects in the right coronary artery (RCA) area from 73% to 88% (p = 0.005) and from 74% to 83% (p = 0.04), respectively, and the accuracy of the method in the left anterior descending (LAD) artery area from 79% to 87% (p = 0.043). It also reduced the number of ambiguous results of the study. CONCLUSIONS AC improved the diagnostic performance of myocardial perfusion study in the detection of CAD and identification of critically stenosed LAD and RCA vessels, with enhanced comfort of study interpretation.