The Belgian carbonate-dominated Devonian (especially the Dinant Synclinorium) has recently been studied for the integration oi palaeoecology, sedimentology and sequential characteristics (Preat & Boulvain, 1988; Preat & Mamet, 1989; Boulvain, 1993). This series, about 1.5 km thick, shows the succession oi silico-carbonate ramp systems and carbonate platforms with slight slope and no real barrier, in the present meaning oi the term. This article consists oi a systematic study of the Belgian-French Upper Eifelian-Lower Givetian stratigraphic interval (Tortodus kockelianus and Polygnathus ensensis conodont zones) for which, so far, no synthesis exists. A sedimentological model for this Eifelian-Givetian, argillaceous carbonate succession enables the recognition of 10 major microfacies. They range rom the open marine (below the storm-wave base) to reefal complexes, open lagoons and peritidal environments near subaerial exposure. The sedimentary model consists oi a homoclinal, storm-influenced ramp system showing a large shoreface extension. Buildups dominated by stromatoporoid-coral patch-reels, crinoidal sand banks, algal or bryozoan shoals are rather isolated and mainly occur within the inner parts oi the ramp, in shallow, oxygenated waters. Storm-generated flows and uniform distribution of the sediments have prevented the development of continuous reefal barriers. The cyclostratigraphical analysis of these Eifelian-Givetian facies will specify the evolution of the third order eustatic curve and establish the palaeotectonic structure of the studied area (Kasimi & Preat, in preparation).