A review is made of theoretical and experimental works on the influence of microroughness on the optical properties of metal surfaces. Interest in these problems has increased substantially in recent years due not only to practical needs but to the discovery of new phenomena arising from electromagnetic field enhancement at rough surfaces. Specific discussion will be presented of light reflection from both comparatively smooth and very rough surfaces. The spectroscopy of optical surface polaritons on rough surfaces and the influence of local electromagnetic resonances on different optical effects will also be discussed. An outline of the recent works on optical methods for diagnosing surface phase transitions, the structure of adsorbed layers and the initial stages of electrocrystallization are given.