An analysis of observation material concerning fog occurrence in Hornsund collected by seven whole-year expeditions of the Polish Academy of Sciences' to Spitsbergen in 1957—58, 1978—1980, 1981—1985 is presented. The frequencies of fog occurrence in Hornsund during a year and in particular months are compared with respective frequencies calculated for Norwegian stations in Svalbard. Data from the Poland territory are also quoted. The dependences of the fog frequency in Hornsund on air masses advection, circulation type, direction and speed of local winds, time of observation and temperature are shortly analyzed. The periods with long-lasting fogs (exampled by synoptic situations that favor them) are discussed more precisely. A short description of main meteorologie processes favoring the occurrence of fog in this part of Spitsbergen is presented.