Surveys prior to the construction of a wind turbine led to the discovery and then the excavation of a Middle Paleolithic deposit at Lislet (Aisne). The Lislet stratigraphic sequence is composed of loess sediments resting on the chalky substrate. All the elements available allows to determine that its age is eemian-weichselian. At the base is an illuviation horizon attributed to the Eemian. The overlying sediments are correlated with the Weichselian Pleniglacial. The orange horizon visible in all the sections is correlated with the Saint-Acheul Complex dated to the Middle Pleniglacial (isotopic stage 3: 59 – 33 ka). An OSL date performed on sediments overlying this orange soil gave 34.9 ± 2.3 ka. The archaeological level is contained in this palaeosol of interstadial rank and is placed in a period of time between the end of the Lower Pleniglacial and the end of the Middle Pleniglacial. The lithic industry (352 artefacts) is oriented towards the production of flakes (Levallois, unipolar, bipolar and polyhedral debitages) but the presence of biface shaping flakes testifies to the transit of this type of piece on the site. A subtriangular biface was found out of context, but its association with industry is very likely. A cultural attribution to the Mousterian of Acheulean tradition is proposed.