OBJECTIVE: To investigate which factors predict the resumption of menstruation by patients with anorexia nervosa (AN). METHODS: Participants were AN patients who, even after weight recovery by inpatient treatment, had prolonged amenorrhea (N=11), AN patients who resumed menstruation after weight recovery (N=9), and age-matched healthy controls (N=12). Anthropometric data and the serum levels of leptin, insulin-like growth factor1 (IGF-1), cortisol, luteinizing hormone (LH), estradiol (E-2), and other hormones were measured at the beginning of the inpatient treatment and after weight recovery. RESULTS: Of the baseline anthropometric and hormonal factors, logistic regression analysis extracted a high serum cortisol level as a predictor of the inhibition of the resumption of menstruation. After weight recovery, the E-2 and leptin levels were significantly higher for eumenorrheic patients than for amenorrheic patients. CONCLUSION: The baseline serum cortisol level was a predictor of the prolonged inhibition of menstrual recovery. (Eating Weight Disord. 15: e226-e233, 2010). (C)2010, Editrice Kurtis