Background There is strong evidence that the mean age of menarche has declined over the last few decades in developed and developing countries. This is of a major concern because of its enormous public health implications. This study aimed to estimate the age of menarche in Kuwait and investigate the association between menarcheal age and academic performance among high school girls in Kuwait. Methods A cross-sectional study was conducted on randomly selected female high school students from private and public high schools in all governorates in Kuwait. Data on the age of menarche were collected by self-administered questionnaire from the students, while data on academic performance were extracted from the students' academic records. Results Of the 907 students we selected, 800 (88.2%) responded. The mean age of menarche was 12.33 [95% confidence interval (CI) 12.18-12.49] years. There was no evidence for significant association between age of menarche and students' academic performance before or after adjusting for potential confounders. Conclusion The calculated age of menarche among contemporary girls in Kuwait is similar to that of the girls in industrialized countries. Early menarcheal age is unlikely to lead to adverse behavior that may affect academic performance in our setting.