Studies of extraction of short peptides using supported liquid membranes containing Aliquat 336 as a carrier are presented. The extractions are carried out from an aqueous donor phase with pH a 10 to an acceptor phase containing salt. The mass transfer is driven by the gradient of salt concentration between these phases. The extraction efficiency is dependent on the composition of water phases, the type and concentration of counter-ion in the stagnant acceptor phase and the flow rate of the donor phase. Moreover, it is also influenced by the concentration and structure of the examined peptides.