AbstractThis 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=.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.Key WordsAcademic Achievement, Brain-Based Learning, Meta-analysis, Neuroscience, Neurophysiologic Learning.In recent years, electrophysiological studies, neuropsychological tests and the use of imaging techniques (Vaid & Hall, 1991; Vigliocco, Vinson, Druks, Barber, & Cappa, 2011; Weintraub, 2000) have created opportunities for researchers in the structural and functional studies of the human brain which have provided clues resulting in big changes for the field of education.By knowing how the brain works, brain-based learning supports learning by discovering the ways of maximum learning (Carolyn, 1997). This approach associates learning with the brain and the way it works, and mentions the positive effects of the brain's features and its enhancing performance on learning. Therefore, it is mainly interested in the development of the brain. Through neuroscience, investigating the relationship between the brain, the neural system and our cognitive behaviors, brain-based learning is increasingly supported by studies, especially with the improvement of MRI, PET and MEG technologies (Hansen & Monk, 2002). Today, tests are carried out with the use of these new technologies. The position of neurons in a living human brain can be color-imaged by systems such as the positron emission tomography and Nuclear Magnetic Resonance Imaging (NMRI). In this way, several variables like memory, emotion, attention, mapping and their effects on learning are studied (Soylu, 2004; Tascioglu, 1994; Thomas, 2001; Weiss, 2000). These studies, both in our country and around the world, provide us with interesting data. For instance, it is revealed that cell clusters examined by imaging techniques don't have systematic structures as supposed, or that the linguistic part of a person isn't in the same place as that of another person (Ergenc, 1994).The essential point of brain-based learning is meaningful learning. Mapping is required to maintain meaningful learning. Mapping means that new knowledge is linked to previous knowledge and the new knowledge is put into the current system (Keles & Cepni, 2006).The phrases of brain-based learning are the ones that make learning meaningful and permanent (Hasra, 2007, p. 40). These phrases are relaxed alertness, orchestrated immersion, and active processing. Caine and Caine (1990) explain these:Relaxed Alertness: It means to create the optimal emotional and social climate for learning. A challenging learning environment with minimal threats should be provided (Gulpinar, 2005). When a person is interested in something, s/he is open to learn, or vice versa. …