Objectives: To investigate the relation between severity of coronary artery disease (CAD) assessed with Friesinger score (FS) and vessel score and myocardial performance index (MPI), also known as Tei index, in patients with Unstable Angina (UA). Methods: The study included 50 patients with UA who were candidate for coronary angiography. All subjects underwent full history taking, complete clinical examination, echocardiographic examination for calculation of MPI and Ejection fraction (EF), and coronary angiography for calculation of FS and vessel score. Results: study population included 23 female (46.0%) and 27 male (54.0%) with mean age (55.9±6.3), Mean MPI was (0.5±0.11), Mean EF was (56.8±6.3), Mean FS was (5.64±2.99), Mean Vessel score was (1.7±0.84). There is statistically significant positive correlation between MPI and severity of CAD as assessed by FS (p value <0.001) and vessel score (p value = 0.001) in patients with UA. Conclusion: Echocardiographic evaluation of MPI in patients undergoing coronary angiography may be applied as a new surrogate marker of the extent of coronary atherosclerosis. It is strongly correlated to severity of CAD as its value was impaired in proportion to increased value of FS & vessel score.