Introduction: No reflow during primary angioplasty is associated with a poor prognosis despite the reopening of the culprit coronary. The aim of our work was to determine the predictive factors of no reflow. Methodology: Single-center retrospective analytical study from June 2000 to December 2016 that included patients presenting with STEMI took care of by primary angioplasty. No reflow was defined according to angiographic criteria: a TIMI flow < 3 (regardless of the Myocardial Blush Grade) or TIMI flow at 3 with MBG ≤ 1, patients were divided into two groups, one group with no reflow and a second group without no reflow. Clinical and angiographic data were compared between the two groups. Univariate and multivariate analysis was performed to determine the predictors of no reflow. Results: The prevalence of no reflow was 24%. In univariate analysis mean age, diabetes, hypertension, tachycardia, hypotension, killip stage 4 left ventricular failure, hyperglycemia > 11, renal failure, left ventricular dysfunction, tritruncal status, common trunk involvement, initial TIMI flow at 0, significant thrombotic load, delay to angioplasty > 6 hours, and predilation were all correlated with no reflow with a p < 0. 05. In multivariate analysis age > 75 years [OR = 6.02, 95% CI 1.4 -27, p = 0.014], tachycardia [OR = 4.3, 95% CI 1.6 -7.4, p = 0.037], delay to angioplasty > 6 hours [OR = 1.3, 95% CI 1.1 -2.1, p = 0.003] and high thrombotic load [OR = 1.5, 95% CI 1.3 -3.2, p = 0.02] were independent predictors of no reflow. Conclusion: No reflow is associated with a poor shortterm prognosis. Its care requires knowledge of predictive factors, prevention and treatment.