The purpose of this study was to determine the efficiency of 4MAT method of instruction in which learning style and cerebral hemispheres are taken into account in teaching the binary operation and its properties in mathematics. The sample of this study comprised 58 ninth grade students in two separate classes in a high school. One of the classes was selected as the experimental group in which 4MAT method of instruction was used; and the other class was selected as the control group in which the traditional teaching was given, and this selection was performed randomly. The data have been obtained primarily from three scales, namely "mathematical knowledge test", "mathematical attitude scale" and "knowledge test on binary operation and its properties". It has been determined that 4MAT method of instruction was more efficient than the traditional method in teaching of the binary operation subject in mathematics. (Contains 2 tables and 1 figure.)