An almost complete plastron, as well as several peripherals and a costalplate of a turtle from the middle Eocene of Saint-Gilles, is presented here.Although this turtle specimen was donated to the Institut royal des Sciencesnaturelles de Belgique (Brussels, Belgium) more than a century ago, itremained undescribed. Its study allows us to recognize the secondpleurodiran in the Belgian fossil record, where, until now, the EoceneNeochelys was the only one known. The Belgian material of Neochelys is known in lower Eocene(early Ypresian) levels, but the new pleurodiran specimen comes from themiddle Eocene (early Lutetian). It is the first partial articulate shell ofa pleurodiran turtle recognized in Belgium, and the only member of thisclade recognized in this country at specific level. The new specimen is arepresentative of the so-called Erymnochelys group, this lineage being known in Africa fromthe Upper Cretaceous to the present but in Europe only during the Eocene.It represents the first specimen of Eocenochelus eremberti identified outside its type locality,the French region of Saint-Germain-en-Laye (Yvelines, Île-de-France),where only one specimen was found. The plastron of the Belgian individualcorresponds to the most complete for this species. Its analysisallows us not only to broaden the range of paleobiogeographical distribution ofEocenochelus eremberti but also to improve the knowledge about the anatomy and variability ofthis taxon.