This study analyses the relationship between aggressive behavior among peers and academic achievement in a sample of 1657 Spanish students (52.2% boys) of Compulsory Secondary Education, ranging in age from 12 to 16 years. Aggressive behavior was assessed by the Antisocial Behavior Scale of the Teenage Inventory of Social Skills, and academic achievement was measured by means of school records. Results reveal that the percentage of girls with high aggressive behavior and three or more failed subjects is significantly higher than the percentage of girls with low aggressive behavior and the same number of failed subjects in grades 7 (d= 0.48), 9 (d= 0.38) and 10 (d= 0.51). Furthermore, no statistically significant differences in academic performance are found between boys with high and low aggressive behavior for any grade level of compulsory secondary education. The multivariate logistic regression analysis shows that aggressive behavior has an influence on low academic achievement in girls (OR= 2.33; CI 95%= 1.49-1.63). Results are discussed taking into account gender and grade level differences.