B a c k g r o u n d: Echocardiography is the first exam to establish the myocardial function in patients with takotsubo syndrome (TTS). However, ECG-Gated Myocardial Single-Photon Emission Tomography (G-SPECT) also allows to calculate left ventricular ejection fraction (LVEF) and can be useful in early stadium of TTS. A i m: To compare LVEF obtained from 99mTc-MIBI G-SPECT and echocardiography in patients with TTS. M a t e r i a l a n d M e t h o d s: Study population: 20 patients in medium age 77 (62–89) with TTS were included. In all patients 99mTc-MIBI G-SPECT and echocardiography was performed on the same day. R e s u l t s: LVEF measured by G-SPECT and echocardiography ranged from 34 to 83% and 38 to 69%, respectively. The LVEF values for ECHO were significantly lower than for SPECT. The correlation between the LVEF was r = 0.76. The calculated correlation coefficient (r) for linear regression analysis was 0.64. The following equation shows the approximate interdependence of both LVEF calculations: LVEF GSPECT = 10.35 + 0.93 * LVEF Echo. C o n c l u s i o n s: G-SPECT tends to overerestimate LVEF compared to echocardiography so these imaging techniques should not be used interchangeably. Calculated equation should be used for comparison of LVEF.