Abstract The sedimentary sequences of the upper Miocene in the Strymon basin in Northern Greece are composed of sedimentary rocks and are separated on an entirely new lithostratigraphic shape. Fossil-fauna has been collected from specific parts of the described geological sections, which mainly include mollusks from Bivalvia and Gastropoda. From laboratory research on the micro-fauna and micro-flora a number of taxonomic units of Foraminifera were determined and representatives of Actinozoa, Bryozoa, Crinoidea, Ostracoda, Otolithus, Diatomeae and Charophyta were found, which give a more-complete biostratigraphical image of the sediments. Based on these investigations with the use of the biofacial analysis, through the study of palaeoecology data of the fossils, three basic types of palaeohabitat and development of organisms were identified and a new palaeogeographic interpretation of the depositional environments in the Miocene basin is given.