This paper investigates the Lower Miocene carbonate succession outcropping in the Monte Lungo Area (Cassino Plain, Central Apennines). The Cassino plain is located in the southern sector of a wide neritic domain known as Latium-Abruzzi platform. Two stratigraphic sections spanning the Upper Aquitanian-Lower Burdigalian, at the locality Peschito and in the summit of the Monte Lungo structure, were analysed in detail. Facies analysis, bioerosion features, biotic assemblages are consistent with an inner ramp environment. The inner ramp was characterized shoreward by a high-energy environment immediately below the littoral zone with low sedimentation rates, passing seaward into sea grasses meadows and associated "maerl" facies, and further seaward into coral carpets. No lagoonal or coastal facies are recognised in the investigated area. The Cretaceous substratum is initially colonized by bioeroders and successively by balanids, later overlain by a 12 m thick interval characterized by pebbly packstone levels, bioclastic packstone to floatstone and red algae branch floatstone. A deepening upward trend from inner to middle ramp is observed in both sections. The presence of Porites, Lithoporella, and Heterostegina in the biotic associations clearly suggests that sedimentation took place in a subtropical (tropical) setting.