A 29-amino acid analog of growth hormone releasing factor (GHRF) was designed in which the sequence of the first six amino acids at the amino terminus was maintained while the postulated amphiphilic helical structure in the remainder of the molecule was optimized. The amino acid sequence of the analog differed from that of the first 29 residues of human GHRF by 13 residues. The peptide was synthesized by the solid-phase procedure in amide and free acid forms, both of which were tested for biological activity.