Linear and cyclic antamanide (ANT) analogues with dipeptide segments Pro2-Pro3, Pro7-Pro8 and both of them replaced by their tetrazole analogue Pro-psi[CN4]-Ala, respectively, have been synthesized by SPPS method and cyclization with TBTU reagent. The peptides were examined for their immunosuppressive activity in a lymphocyte proliferation test (LPT).