This thesis is based on samples and data collected during investigation of demersal communities conducted in a framework of international projects EU MEDITS from 1994 to 2008 and FAO AdriaMed from 2008 to 2010. Objectives of this thesis were description of composition of demersal communities and demographic structure of populations of most important species living in the deep Adriatic, comparative analysis of composition of demersal communities with respect to depth, analysis of changes that occurred in a period from 1994 to 2008, and creation of recommendations for the protection of the investigated area. During this study total of 339 species of fish, crustaceans and cephalopods were recorded in the entire study area. Three species new for the Adriatic were recorded in the deepest part. On the continental slope, most common species by biomass were Lepidopus caudatus, Merluccius merluccius and Micromesistius poutassou, while in the deepest part of the Adriatic most common species were Galeus melastomus and Trachyrhynchus trachyrhynchus. In a period from 1994 to 2008 a decrease in population densities were noted in all depth strata and it was especially evident in shallow areas. Multivariate analysis of composition of demersal communities showed statistically significant differences between areas in the deep Adriatic. Further more, demographic stratification of population structures of the most important species was noted with respect to depth. The recent state of demersal communities in the deep part of Adriatic indicates a need for introduction of preventive protection measures for this area.