The light transmission through metallic films with different types of nano-structures was studied both theoretically and experimentally. It is shown, analytically, numerically and experimentally, that the positions of the surface plasmon resonances depend on the nano-structural details. Those can be changed from sample to sample or in given sample by applying an external dc electric or magnetic field. The dependence of transmission spectrum on the shape of holes (inclusions) and external fields can be used for manipulation of the light transmission, as well as the polarization of the transmitted light and other optical properties, by external field. Two complementary situations are considered: a metal film with dielectric holes and a dielectric film with metallic islands. In the case of metallic islands, we propose two ways of controlling plasmon resonance frequency: changing the aspect ratio of the elliptical (or rectangular) islands and changing their mutual distances. For this case a new analytical asymptotic approach for calculating the optical properties of such plasmonic systems is developed. The results of our analytical and numerical studies are in good qualitative agreement with experiment.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.