bookmark MCPep Explores the interactions of helical peptides of up to 50 residues with membranes of various types. MCPep is a server designed for non-experts wishing to perform Monte Carlo (MC) simulations of helical peptides in association with lipid membranes. The software simulates the peptide in the aqueous phase and membrane environments, both described implicitly. It reports the main determinants of peptide-membrane interactions, e.g. average location and orientation in the membrane, free energy of membrane association and the peptide's helical content.