Purpose: To investigate the effect of epilepsy and/or valproate (VPA) monotherapy on physical growth, weight gain, pubertal development, and hormonal status in adolescent girls with epilepsy. Methods: The study group included 88 consecutive female patients with epilepsy aged 6-20 years (28 premenarche, 60 postmenarche) attending an endocrinology institute of a major tertiary center. Forty-five patients were under treatment with VPA, and 43 were before treatment initiation. The groups were compared for the relevant biochemical, anthropometric, ultrasonographic, and endocrine parameters. Results: No statistically significant differences were found in any of the parameters studied between the groups, as a whole or by menarche status. The treated postmenarcheal subgroup had a higher mean testosterone level than the untreated postmenarcheal controls (1.83 ± 0.65 vs. 0.88 ± 0.24, p = 0.006). Body mass index-standard deviation score (BMI-SDS) was 0.75 in the treated group and 0.63 in the untreated group; rates of obesity were 16.3% and 15.5%, respectively. No between-group differences were found in menses irregularities, hirsutism, or acne. No correlation was found between duration or dosage of treatment and BMI-SDS, height-SDS, or androgen level. The treated group had higher levels of thyroid-stimulating hormone and lower levels of free thyroxine than did the untreated group, although still within normal range. Conclusions: Long-term treatment with VPA in girls with epilepsy is associated with increased testosterone levels after menarche, without clinical hyperandrogenism, polycystic ovary syndrome, or an increase in BMI-SDS. VPA is a good treatment option in this age group but should be accompanied by careful endocrine observation.