This article attempts an overview of the evidence of settlements that can be studied at the end of the Middle Paleolithic period (75-40 Ka BP) in Île-de-France. As in the Paris Basin, the last Neanderthal settlements have long been the poor relative of regional research, particularly because of taphonomic filters affecting the outdoor recording of the Weichselian glaciation. However, the last decade has seen a multiplication of either well dated evidence or evidence sharing strong typo-technological affinities with discoveries made in various neighbouring regions. Noting the significant sedimentary disparities across the Paris Basin during the Lower and Middle Pleniglacials, it is necessary to return to specifics, limitations and opportunities offered by the regional context. It is from this perspective that recent discoveries, and older evidence, are examined in the preventive and programmed framework. The report reaffirms the interest in the slopes with outcrops of sand of Fontainebleau, very present in the Ile-de-France landscape and which seem to offer «windows of conservation» which are favourable and sometimes exceptional. This is illustrated by the Bossats site in Ormesson (Seine-et-Marne). Its glacial sequence and the discoidal industry of level 4, under a Chatelperronien level, open up rare perspectives for the study of the last Neandertal populations of northern Europe. The article provides a report on the Middle Paleolithic industries of this site.