The Mediterranean area is particularly sensitive to environmental and climatic changes. In the Mediterranean basin, research undertaken over the past 30 years has shown that non-marine molluscs are useful bioindicator to document the Holocene environmental evolution. However, in Morocco and other Magrebine countries, palaeoenvironmental reconstructions using land snails are in the early stage of research. Analyses of fossil molluscan assemblages are based on a palaeoecological approach which needs good knowledge on modern malacofauna and their habitat but, in Northern Africa, lack of accurate and exhaustive investigation on it make work challenged. At Aït Said ou Idder, a 3 meterhigh tufa sequence, rich in shells, has been discovered in 2015. Geomorphological, chronostratigraphical and malacological investigations have been carried out on this Middle Holocene tufa sequence during my master degree work. Malacological results obtained on 36 samples covering the 6600 – 4600 cal. B.P. succession are here presented: 36 taxa were identified, including 24 terrestrial species. During the Middle Holocene, three main environmental phases have been identified. Between 6600 and 6100 cal. BP, a mesophilic environment is characterized by open and dry areas (Otala tingitana, Cochlicella barbara, Truncatellina cylindrical and a Geomitrid species) with some paludal zone (with Succinelle oblonga, Oxyloma elegans, Vertigo angustior, Zonitoides nitidus). Between 6100 and 5600 cal. BP, a durable marshland developed characterised by Oxyloma elegans, Vertigo moulinsiana, Vertigo antivertigo, Vallonia enniensis and Carychium minimum. Between 5600 and 4600 cal. BP, the paludal zone tended to disappear while an open and sclerophyllous environment developed with the rising proportion of Geomitrid species and Cochlicella barbara. A geochemistry study has been concurrently undertaken and allow comparing and discussing malacological results to carbon and oxygen stable isotope data. Geochemical results support these environmental patterns. Data from Aït Said ou Idder tufa is very complete and new for Morocco. The malacological study contributes to the reconstruction of the Middle Holocene environmental history of the Mediterranean area and document Holocene Moroccan malacofauna