This study was carried out to investigate the flipped learning method on students' academic achievements compared to the traditional method. Aiming to identify the effect size of the flipped learning method (FL) on academic achievement, metaanalysis method is used in this study used. 8 postgraduate theses and 5 articles, which met the inclusion criteria and could be accessed, are included in the meta-analysis. The heterogeneity value of the included studies was first calculated, and then all achieved values (Q=6.148, p>0.05, 12=0.00) indicated that there is homogeneity among the studies. This shows that the fixed effects model could be used in the calculation of effect sizes. General effect size of the studies investigating FL's effect on academic achievement compared to the traditional teaching method is 0.744 with an error of 0.080 according to the fixed effects model. This effect level does not differ by the educational level of sample group, type of study and year of publication.