Regularly striped patterns are observed when imaging supported, mixed bilayers of the phospholipid DPPC and a synthetic α-helical transmembrane peptide (WALP) with contact mode AFM at ambient temperature. Temperature dependent AFM is used here as a tool to observe the temperature behavior of this system. Melting in a 2 mol% peptide/DPPC system starts at 36°C. The domains lie higher than the surrounding lipid bilayer at low temperatures (<36°C), but change to lower lying areas above that temperature. In contrast, pure lipid bilayers do not start melting until 40.5°C. Melting seems to start at defects present in the lipid bilayer.