The LH/FSH ratio values between gonadotropins dosed with a monoclonal antibody assay (IRMA) in the micropolycystic ovary syndrome (PCOS), are discussed and compared to those obtained with the classic assays using polyclonal antibodies. Because of the higher selectivity of this IRMA assay it is noteworthy that the cut-off value between normal and PCOS patients is now equal to or above one. The evaluation of the LH/FSH ratio between the peak values of the two gonadotropins after a GnRH 100 micrograms iv bolus, may be useful in the diagnosis of PCOS in those patients who present an LH/FSH less than 1 in basal conditions even in the presence of clinical and ecographic aspects of PCOS.