Résumé : Immunoperoxidase electrophoresis, combining SDS-ME-PAGE and the 'double bridge' immunoperoxidase staining was applied to crude human pituitary homogenates. With anti-hGH and anti-hPL sera, 4 hGH-related monomers were characterized: a M(r) 22 000 peptide corresponding to hGH; a M(r) 20 000 peptide corresponding to the known hGH variant and two unknown hGH variants (M(r) 65 000 and M(r) 75 000). With anti-ovine, rat and human PRL sera, 4 PRL-related monomers were immunostained: one comigrated with purified hPRL (M(r) 25 000), and 3 were unknown (M(r) 29 000; M(r) 45 000; M(r) 16 000).