This paper considers a computational model using the peptide- antibody interactions.Th ese interactions which are carried out in parallel can be used to solve NP-complete problems.I n this paper we show how to use peptide experiments to solve the Hamiltonian Path Problem (HPP) and a particular version of Set Cover problem called Exact Cover by 3-Sets problem.W e also prove that this of model of computation is computationally complete. © Springer-Verlag Berlin Heidelberg 2002.