The extraction of short peptides, through a supported liquid membrane containing di-2-(ethylhexyl)phosphoric acid (D2EHPA) as a carrier was investigated. The extraction was carried out from the aqueous donor phase with pH 3 to a more acidic acceptor phase. The proton gradient between the donor and the acceptor phase was the main driving force of the mass transfer in this system. The influence of various parameters such as diluent of the carrier, pH of the donor and acceptor phase, peptide structure and concentration on the extraction efficiency was presented.