Recent advances in the synthesis and characterisation of plasma polymerized thin organic coatings has enabled new insights into the design of interfaces for specific interactions with biological molecules. Optical techniques such as surface plasmon resonance and waveguide mode spectroscopy have been used to monitor in real-time the reactions of proteins, antibodies and DNA at the interface of different plasma polymerised films. Combining these techniques with AFM, FTIR and XPS analysis has demonstrated a tremendous flexibility in surface design, plasma polymer structure and surface reactivity. The chemical composition, the macromolecular structure and the ability to form a 3-dimensional interface open up new concepts for the design of biomaterial surfaces. The interactions of proteins, antibodies and DNA can be correlated to plasma deposition conditions and subsequently the chemical and physical properties of the deposited layers.