A study of the efficiency of partition chromatography for the purification of peptides as a function of structure has been undertaken. A series of 19 omission analogs of camel β‐endorphin and of some of its partial sequences have been synthesized with each analog missing only a single amino acid. Their chromatographic properties have been examined with use of the Martin hypothesis and the RMconcept, and a hydrophobicity scale for the amino acid side chains was obtained. To a first approximation a correlation with the Tanford hydrophobicity scale for amino acids was found. A decrease in hydrophobicity has been observed with increasing chain length and is discussed in terms of column efficiencies required for the purification of synthetic peptid