The topic of research are the clastic deposits of the Istrian flysch, which together with the Foraminiferal limestones, were deposited within a Dinaric foreland basin that existed in Istria during the Middle Eocene. The flysch consists of hemipelagic marls and various gravity-flow deposits which are the main focus of this study. For the purpose of the research, 13 sedimentological logs and four additional outcrops were analyzed. Sedimentary facies include: olistoliths, megabeds, rudite turbidites, arenite turbidites, marl with sparse beds of arenite, massive marl, slumps and landslides. The megabeds are composed of lithoclasts derived from older neritic limestones underlying the flysch, bioclastic sediments derived from synchronous carbonate ramps, and reworked basinal marls. Bioclastic fossil detritus is also one of the main components of rudite turbidites, while siliciclastic material is found only in arenite turbidites in the upper part of the Istrian flysch succession. Paleoflow measurments from siliciclastic strata indicate a dominant paleotransport direction towards the southeast, while the direction of carbonate beds was towards the north. According to the investigated facies, it is concluded that the Istrian flysch was deposited in deep-water paleoenvironments, base-of-slope and the basin plain. The deposition of megabeds and other deposits was influenced by tectonic activity related to the propagation of Dinaric structures. Based on the analysis of planktonic foraminifera and limestone nanoplankton assemblages, the age of the Istrian flysch was confirmed as Middle Eocene.