Available treatments for Anorexia Nervosa (AN) have demonstrated limited efficacy. Moreover, therapeutic interventions focusing on neural correlates and on populations with AN in adolescence are limited. A double-blind, placebo-controlled, add-on randomized trial (RCT) was conducted to study the efficacy of excitatory transcranial direct current stimulation (tDCS) over the left prefrontal cortex in improving the clinical outcome of traditional treatment in adolescents with AN. Fifty girls with AN (aged 10 to 18 years) underwent 18 sessions of tDCS treatment (active or placebo) over the PFC (anode F3 / cathode F4) in conjunction with psychiatric, nutritional, and psychological treatment, for a total of six weeks, three times a week. Physiological, neurophysiological, and psychopathological measures were collected at baseline, at the end of treatment, and at 1, 3, and 6 months follow-ups. The results showed a progressive increase in body mass index in all participants. However, the value of the "Eating Disorder Risk" subscale of the EDI-3 questionnaire showed a significantly higher decrease at the end of treatment and at follow-ups only in the active tDCS group, indicating a trend towards score normalization. The analyses of physiological and neurophysiological outcomes are ongoing. This is the first tDCS RCT with a large sample size on adolescents with AN. The results seem promising to consider tDCS a valid therapeutic perspective for the treatment of AN in adolescence, with the advantage of being able to be used in association with psychotherapy and nutritional treatment to enhance their effects.