A method is described utilizing polyethylene glycol (PEG) combined with a double antibody for separation for rapid radioimmunoassay (RIA) of human luteinizing hormone(hLH). The total assay time is 3 hours with a 1-hour incubation period. Reliable comparisons with the 3-day assay have been shown. The average between-assay coefficient of variation was 11%, whereas the average within-assay coefficient of variation was 6%. The sensitivity of the assay was 7.5 mIU/ml. It is suggested that this reliable and rapid RIA for hLH will prove to be a valuable adjunct in the treatment of patients when timing of ovulation is imperative, such as for artificial insemination and harvesting of maturing human oocytes.