Research into the effects of out-of-school-time mathematics and science lessons on academic performance has thus far proved inconclusive. The relationship between the two requires investigation to elucidate the benefits of these lessons or lack thereof. Using data from the 2009 Program for International Student Assessment (PISA), this study examined the relationship between out-of-school-time mathematics and science lessons and academic performance among 15-year-olds in Hong Kong, China; Korea; Shanghai, China; and Singapore. In light of different cultural contexts, educational standards, and societal norms, and after accounting for gender and family socioeconomic status, which takes into consideration parents' occupational status, years of education, and home possessions, regression analyses revealed inconsistent results across these countries. The study concludes with the implications of the findings and scope for future research, underscoring the need for further investigation that addresses educational disparities in Asia and globally.