Objective: Platelets play an important role in both initiation and propagation of acute coronary syndromes. We sought to evaluate the predictive value of mean platelet volume (MPV) in young patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS). Methods: This is a retrospective observational study; evaluating the MPV values of 79 NSTE-ACS patients aged under 45 years and 45 control subjects having normal coronary anatomy. NSTE-ACS group was composed of 41 non-ST elevation myocardial infarction (NSTEMI) and 38 unstable angina pectoris (USAP) patients. MPV was measured using an automated hematologic analyzer called Coulter counter. The predictive value of MPV was evaluated using logistic regression analysis and comparison of MPV between NSTE-ACS and control groups was performed by Mann-Whitney U test.Results: The MPV was found to be significantly higher in the NSTE-ACS compared with control group (8.49±1.22 versus 7.78±0.65 fL, p=0.001). In logistic regression analysis, MPV was found to be an independent predictor of NSTE-ACS (OR=3.1, 95% CI 1.2-8.2, p=0.022). The MPV values of NSTEMI group were not significantly different from USAP group (8.78±1.38 versus 8.17±0.95 fL, p=0.66). Similarly, the MPV values of the 3 groups (Control, USAP and NSTEMI) were found to be significantly different (7.78±0.65, 8.18±0.95, 8.78±1.38 fL respectively, p=0.001).Conclusion: In conclusion, MPV was found to be elevated in NSTE-ACS patients compared with control subjects in young population. In addition, increased MPV was established to be an independent predictor of NSTE-ACS.