Alterations in the secretion of iodothyronines, cortisol, testosterone and growth hormone have previously been described in anorexia nervosa. We have studied prolactin and gonadotropins secretion in 23 cases of anorexia nervosa. Prolactin secretion was normal. Modifications in gonadotropins release were observed. However they could not be always related to weight loss since amenorrhea could either precede weight loss or still be present after return of the weight to normal. In all cases, FSH release after LHRH stimulation was normal. No increase in LH levels was observed after LHRH injection when the weight was 70% below the ideal weight. With increasing weight, LH release progressively recovered and normal LHRH-induced LH release was obtained when the weight was above 90% of the ideal weight. At normal weight, the ratio of LH/FSH was normal in patients menstruating less than 3 months after the test, while the ratio was low in non-menstruating females. In conclusion, when the weight was insufficient basal levels of FSH and LH and responses after LHRH stimulation corresponded to a prepuberal stage. An increase in the LH/FSH ratio and a normal LH/FSH ratio preceeded the recovery of menstruations. In about 1/3 of the cases, such an evolution was not observed without any satisfactory explanation. Other factors than weight may be involved, especially when the amenorrhea persists after weight recovery.