Background/Purpose: Before school exercise programs (BSEPs) give students time for breakfast and add time to their daily physical activity. However, the effects of BSEP on physical fitness and academic achievement in the classroom remain unclear. The purpose of this study is to examine the effects of BSEP on cardiorespiratory fitness and academic performance among fourth- and fifth-grade students. Method: A retrospective case-controlled design was used in this study. Fourth and fifth graders (N = 84) were participants, half signed up for BSEP that met once a week for 10 weeks. A retrospectively case-controlled comparison group was generated from the classmates of those in BSEP in the same school. All students took PACER and statewide academic performance assessments. Multivariate analysis of covariance for student cardiorespiratory fitness, and mathematics and reading, were conducted, adjusting for pretest performances. Analysis/Results: There were improvements for both groups in academic performances and cardiorespiratory fitness. The cardiorespiratory fitness and reading test improvements were greater in the BSEP group than those in the comparison group, controlling for their pretests. However, there was no significant difference in student mathematics test performances. Conclusion: Students in BSEP group benefited from participating in the program with greater improvement in cardiorespiratory and reading test performances than the comparison group. These findings suggested that providing a BSEP once a week for 45 min may be beneficial to fourth and fifth graders.