The chromatography of the peptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 on the cation-exchange cellulose Whatman Express-Ion Exchanger C has been investigated. Scale-down studies both in batch and using Mini Columns demonstrated a binding capacity of similar to 300mg per dry g and a recovery following desorption of similar to 96%. The separation was scaled-up 40-fold to a laboratory column, where 100% (w/w) of applied peptide bound at 200cm h(-1) to give an operating capacity of similar to 90mg per dry g. Following desorption, recovery was similar to 98% with some further purification of the peptide.