Studies of optical properties of aggregated films have usually been performed by considering the properties in the direction parallel to the film surface and, therefore, information on the films was not complete. The techniques of spectroscopic reflection and transmission ellipsometry (RTELL) at variable incident angles developed by our laboratory were particularly suitable for obtaining the anisotropic optical constants for such films with good precision, thus fully characterizing the optical behavior of films. in the present study, aggregated gold films were prepared using solutions containing gold nanoparticles, giving films with a very low filling factor. With the help of an automated RTELL system, the anisotropic optical constants have been determined in the spectral range from 300 to 800 nm. The results obtained showed a striking difference between the parallel and the perpendicular optical constants. This difference was well accounted for by using an effective-medium theory, approximating the nanoparticle clusters to rotational ellipsoids.