significantly increase during puberty. The goal of this research is to evaluate changes during puberty which could have genetic and environmental influences on a broad spectrum of disordered eating attitudes and behaviors. Methods. Participants were 158 pairs of adolescent female twins, categorized in two groups according to menarche stage (pre or post). ED measures: Disordered eating attitudes and behaviors were assessed by means of the Children’s Eating Attitudes Test and four sub-scales of the Eating Disorders Inventory: Drive for thinness, Body dissatisfaction, Ineffectiveness, and Perfectionism. Intra-class correlations in monozygotic (MZ) and dizygotic (DZ) twins were calculated separately in premenarche and premenarche group for each ED subscale Results. 48 premenarche twins (30 MZ twins and 18 DZ twins) and 110 premenarche twins (66 MZ and 44 DZ twins) were included. The intra-class correlations suggested no genetic influence on the total ChEAT score of participants at the premenarche stage. For the premenarche participants, however, sources of variance suggested a very high heritability. Regarding the EDI sub-scales, only the trait “Ineffectiveness” exhibited a moderate heritability among premenarche subjects, while all the four eating sub-scales showed moderate heritability estimates in the premenarche stage group. Conclusions. Our findings reveal that there are significant differences in genetic and environmental effects on eating attitudes and behaviors depending on being in a premenarche or premenarche stage. Therefore, clinicians should pay attention to female adolescents at high risk of developing ED, especially during the critical period of menarche.