A recently developed implicit solvation model is applied to Monte Carlo simulations of peptides in bilayer-mimetic and polar environments. The model employs the formalism of atomic solvation parameters and reproduces experimental data. Solvent effects on the structure of the following peptides were studied: 20-residue poly-Leu and poly-Val, transmembrane helix A of bacteriorhodopsin, magainin2. It was shown that a membrane-like environment considerably promotes α-helix formation (all the peptides were found to be α-helical), while simulations in water reveal helix distortion. Consistency of the results with experimental data and further implications of the model are discussed.