This study's aim is to measure the effect sizes of the quantitative studies that examined the effectiveness of brain-based learning on students' academic achievement and to examine with the meta-analytical method if there is a significant difference in effect in terms of the factors of education level, subject matter, sampling size, and the countries where the studies were carried out. Meta-analysis is the method employed in order to statistically combine the quantitative data collected from many studies of the same topic, and to reach a general conclusion from the results. In this respect, following the literature research, 31 studies (42 effects) which investigated the effectiveness of brain-based learning on students' academic achievement between the years 1999-2011 met the inclusion criteria, were reported in English and Turkish, and were included in the meta-analytical research. The findings indicate that 35 out of 42 comparisons had positive effect sizes. It revealed that brain-based learning has a positive but medium effect (d = 0.640) on students' academic achievement. In addition, when compared with the studies conducted in Turkey and the USA, it drew the conclusion that there is a significant difference between the groups while there is no difference in any effect sizes in terms of education level, subject matter and sampling size.