Organic film has been deposited by the plasma polymerization of pyrrole. The elemental composition of the film was determined by elastic recoil detection (ERD) and Rutherford backscattering spectroscopy (RES). Fourier transform infrared (FT-IR) and X-ray photo-electron spectroscopy (XPS) techniques have been used to characterize it. The reflectance and transmittance data covering the ultraviolet (UV), visible and near-IR regions were used to calculate the complex refractive index, N(omega) = n + ik, using the transfer matrix method. On this basis, a sum rule involving imaginary part of complex dielectric function was applied to estimate the proportion of sp(2) carbon atoms in the deposited plasma polymer film, and the optical properties of the film have been studied in detail.