SUMMARY The results of the application of a solid-phase radioimmunoassay for follicle-stimulating hormone (FSH) to 376 24-h urine specimens assayed routinely by the ovarian augmentation method for FSH, and 663 24-h urine specimens assayed routinely by the uterine weight method for total gonadotrophins, are presented. The correlations between the immunoassay and the bioassays were significant and about 70% of the results were in the same categories whichever method was used. The use of the radioimmunoassay for the clinical assessment of pituitary—gonadal function is discussed.