Self-assembled monolayers of α-helical peptides were prepared on gold and the effects of the monolayer structure on long-range electron transfer through the helical peptides were studied. Electron transport properties of helical peptides were investigated using atomic force microscope with a conducting tip. The helical peptides contained 8, 10, 12 and 14 amino acids residues. A cysteamine linker at the C-terminus and cystamine residue (with Boc protected amino moiety) at the N-terminal were introduced in order to provide covalent contact either with gold substrate or tip. Current-voltage characteristics of these junctions were probed as a function of SAM thickness and the load applied to the microcontact. The electrical behavior and the exponential dependence of current vs peptide chain length are consistent with coherent, nonresonant electron tunneling across the SAM. These measurements show that conducting probe-AFM is a reliable method for fundamental studies of electron transfer through small numbers of molecules. The ability to vary the load on the microcontact is an important feature of these junctions, whichopens opportunity to explore electron transfer efficiency as a function of molecular deformation.