Antimicrobial peptides (AMPs) are naturally occurring polymers that can kill bacteria by destabilizing their membranes. A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to better understand the action of the AMP chrysophsin-3 on supported lipid bilayers (SLB) of phosphatidylcholine. Interaction of the SLB with chrysophsin-3 at 0.05 mu M demonstrated changes in frequency (Delta f) and energy dissipation (Delta D) that were near zero, indicating little change in the membrane. At higher concentrations of chyrsophsin-3 (0.25-4 mu M), decreases in Delta f of up to 7 Hz were measured. These negative frequency changes suggest that mass was being added to the SLB, possibly due to peptide insertion into the membrane. At a chrysophsin-3 concentration of 10 mu M, there was a net mass loss, which was attributed to pore formation in the membrane. QCM-D can be used to describe a mechanistic relationship between AMP concentration and interaction with a model cell membrane.