A novel chemical platform based on branched piperazine-2,5-dione derivatives (2,5-diketopiperazines) for creating orally available biologically active peptidomimetics has been developed. The platform includes a diketopiperazine scaffold with “built-in” functionally active peptide fragments covalently attached via linkers. The concept was applied to two hemostimulatory drugs, the dipeptide thymogen (GluTrp) and the tripeptide stemokin (IleGluTrp). Preparation of a series of respective derivatives is described. Of the five synthesized analogues, three demonstrated high hemostimulatory activity in vivo on intact mice and on ex vivo irradiated bone marrow cells. Prospects of further development of the concept are discussed.