Camel synthetic beta-endorphin focused in three bands by isoelectrofocusing on 1 mm polyacrylamide thin gel. All the bands have opioid activity, measured on guinea pig ileum, and radioimmunologically react with beta-endorphin antiserum. Since beta-endorphin from rat pituitary gland, particularly from the neurointermediate lobe, also focused in several bands, we hypothesized that the camel peptide occurs in different conformations. A quick, simple technique based on histoelectrofocusing is proposed as a good approach to separating and measuring beta-endorphin from rat pituitary lobes. The method gives very high recovery.