Abstract: A peptide of the formula ##STR1## has been isolated from thymosin fraction 5 (TF-5) and synthetically produced. This peptide, which has 100% homology with a region of histone 2A is able to stimulate and enhance the production of growth hormone (GH) and prolactin (PRL) by anterior pituitary cells. The peptide can be used alone or in combination with another growth hormone stimulant, such as growth hormone releasing factor (GRF), or prolactin hormone stimulant, such as thyrotropin releasing hormone (TRH) to increase the production of GH and PRL beyond that achievable with GRF and TRH alone.