Background & Objective: Obesity is one of the problems associated with cardiovascular complications. Patients' heart function improves after sleeve gastrectomy. Global Longitudinal Strain (GLS) is one of the methods used to monitor heart function before and after sleeve gastrectomy. In this study, we evaluated the echocardiographic parameters pre and post sleeve gastrectomy. Materials & Methods: In this cross-sectional study, 22 patients including 17 female and 5 maleundergoing sleeve gastrectomy were studied. They had referred to Shariati Hospital in Tehran during 2019 –,2020. All patients underwent 2D echocardiography using speckle-tracking to evaluate left ventricular function and measure GLS. Results: Data analysis showed that GLS increased after surgery compared to preoperative period (15. 4 ±,3. 8 vs. 18. 4 ±,3. 04). Also, PAP, LVEDV, LVESV, LVDD, LVDS and AO were higher in the mentioned period,these findings were statistically significant (p-value <0. 05). However, the RVSM mean, TAPSE, RVFAC and LVH parameters were higher post-surgery in comparison to the pre-surgery,a significant relationship was observed between the parameters before and after surgery. Conclusion: It can be concluded that GLS method, which evaluates echocardiographic parameters in obese patients undergoing sleeve gastrectomy can be highly significant in monitoring patients.