The attachment of fibrinogen, bovine serum albumin, and immunoglobulin on continuous wave (CW) and pulsed plasma polymerized di(ethylene glycol) monovinyl ether was studied using surface plasmon resonance (SPR) spectroscopy and waveguide mode spectroscopy (WaMS). Structural analysis of the films was carried out using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. Plasma conditions employed during depositions produced significant differences in the chemical and physical properties of the resultant polymer films. Films deposited under CW and higher plasma duty cycles showed relatively high refractive indices (n > 1.57) and essentially a constant thickness if immersed in aqueous buffer solutions and exhibited a high adsorption affinity for proteins. In contrast, films produced under lower plasma duty cycles were of lower refractive index (n < 1.4), exhibited significant swelling if immersed in aqueous buffer, and were extremely effective in preventing protein adsorption. The SPR and WaMS data suggest that the relatively non-cross-linked films produced at the lower duty cycles exhibit hydrogel-like behavior when immersed in aqueous solutions. It is believed that these hydrated films are responsible for the remarkably effective nonfouling properties of the films deposited at low duty cycles. The relationship between film structure, polymer stability in aqueous buffer, and protein binding affinities are discussed.