The behavior of terminally blocked amino acids, N-acetyl alanine amide (NAA), N-acetyl leucine amide (NAL), and N-acetyl glutatmine amide (NAQ) at the 1-octanol/water continuum interface was investigated by Monte Carlo simulation with the solvation free energy density (SFED) calculation method. All the model amino acids have free energy minimum near the interface. These amino acids can have various conformations such as alpha-helix, beta-sheet, and C7-eq, however the minimum energy conformations are obtained as a-helix for all the model amino acids at the interface region. (C) 2002 Elsevier Science B.V. All rights reserved.