Experimental and theoretical studies are made into optical and magnetooptical properties of two- and three-layer structures (Cr/Fe, Fe/Ag, Cr/Fe/Ag) with variable thickness of chromium and iron films. It is found that effective optical constant variations with film thickness are described well within the framework of the theory based on a consideration of multiple reflections from metallic medium interface. A similar statement is true for angular and thickness dependences of equatorial Kerr effect. A discrepancy between experimental and calculated results is observed at film thickness less than 3 nm.