The Devonian to Permian ostracode assemblages in Belgium may be subdivided in six major groups characterizing non-marine through «brackish» and shallow marine into deep marine shelf and «basin» environment. A broad-brush review of their stratigraphical distribution reveals that mixed marine faunas are the most widely extended in the Devonian and Carboniferous. Following the Caledonian orogeny there are tendencies towards «brackish-water» (oligohaline?) assemblages during the Lower Devonian. But since the Givetian also open marine shelf associations are found and even Entomozoans and Thuringian-type ostracodes (indicative for «deep shelf» to «basin») in the Upper Frasnian and basal Upper Famennian. This succession suggests a transgressive trend for the overall depositional environment, reaching its acme in the Late Devonian. The subsequent regressive tendency starts in the late Famennian (Fa2c) and Dinantian with the frequent occurrence of mixed marine assemblages which alternate in time and space with open marine shelf faunas. The culmination of this overall regression in Westphalian times is marked by the successive appearance of «brackish- water» and non-marine ostracode assemblages followed by the disappearance of, respectively, the mixed marine faunas (base Westphalian C) and «brackish-water» ostracodes (Upper Westphalian C). The isolated occurrence of a «brackish-water» ostracode in the red beds of the Thuringian reflects a short- lived marine incursion during that period.Some examples of shallow marine nearshore («mixed marine» and «brackish-water») assemblages from the Upper Famennian to Permian are shown, which have been dated by miospores.