The Mathematics performances among senior secondary school students have been observed to be very poor in SSCE examination. Several researches have been conducted in that regards and observed that one of the factors responsible for this pathetic situation is lack of motivation. Thus, this research work investigated the effect of intrinsic motivation on students' performances in mathematics in Gombe metropolis of Gombe state. The result of this study indicated that the experimental group performed significantly better than the control group in Mathematics Achievement Test (MAT), this implies that the experimental group performed better than the control group. Based on the findings the study concluded that motivation has significant effect on student's performance in Mathematics. That motivation has no significant effect on student's academic performance in Mathematics. This book is strongly recommended to students, Mathematics teachers, Parents, and Stakeholders in field of education in order to improve students' achievement in Mathematics.