Peptide-terminated monolayers were formed through a Huisgen cycloaddition reaction between an alpha-helical peptide containing two propargylglycine unnatural functional groups 20 angstrom apart and an alkanethiol self-assembled monolayer (SAM) on a gold surface containing 25% surface density of reactive azide terminal groups. The azide- and peptide terminated surfaces were imaged by scanning tunneling microscopy (STM) using low tunneling current of 10 pA. On the peptide-terminated surface, oblong and similar to 30 angstrom long and similar to 20 angstrom wide were. observed and attributed to individual surface-bound alpha-helical peptides oriented parallel the gold surface. These. features covered an area of the surface corresponding to a density of 0.11 +/- 0.01 peptides nm(-2), compared with a theoretical density of peptides nm(-2) for a fully reacted surface. Finally, no evidence of peptide aggregation was observed on either short (<10 nm) or long (similar to 100 nm) length scales.