Since the 1970s there has been a growing interest in analysing sex differences in psychological variables. Empirical studies and meta-analyses have contributed evidence on the differences between male and female individuals. More recently, the gender similarities hypothesis has supported the similarity of men and women in most psychological variables. This study contributes information on women's greater empathic disposition in comparison with men by means of a longitudinal design in an adolescent population. 505 male and female adolescents aged between 13 and 16 years were evaluated at two different moments (grade 2 and grade 3, lower secondary education). They completed the Index of Empathy for Children and Adolescents by Bryant and the Interpersonal Reactivity Index by Davis. The results confirm a greater empathic response in females than in males of the same age, differences growing with age. The sizes of the effect estimated in the second evaluation (average age 14 years) are large for emotional empathy and medium for cognitive empathy.