The plasma membrane receptor for GnRH in bovine anterior pituitaries has been solubilized with the cholic acid derivative detergent 3([3-cholamidopropyl)dimethylammonio]propane sulfonate. The soluble receptor in the supernatant from a 100,000 × g × 90 min centrifugation displays high affinity, saturability and specific binding to the agonist, [DAla6,NαMeLeu7, Pro9-NEt]-GnRH. The dissociation constant, KD, for the soluble receptor is 0.56±0.07 nM (mean ± SEM) and the number of sites, RO, is 85±17 fmols/mg protein. For the membranebound receptor the KD is 0.50±0.04 nM and Ro is 300±18 fmols/mg protein. The relative potencies of GnRH and the potent antagonist, [Ac-Δ3<pro1,pFDPhe2, DTrp3,6]-GnRH are similar for both the soluble and membrane-bound receptor.