The fossiliferous sites of Nikiti are located north of the homonymous village at the beginning of the Sithonia Peninsula in Chalkidiki (Macedonia, Greece). The Neogene deposits of Chalkidiki outcrop mainly in its western part and consist of four successive formations: Antonios Fm. (clastic, fluvial; early/middle Miocene – ?Vallesian), Triglia Fm. (fluvio-terrestrial; late Miocene), Trilophos Fm. (marine-brackish; end of Miocene) and Gonia Fm. (fluvio-lacustrine; Pliocene). In the Nikiti area, two different formations were recognized in the Neogene deposits. The clastic Nikiti Fm. overlays unconformably the metamorphic basement and consists of loose, cross-bedded conglomerates, alternated with lenses or lenticular intercalations of red-brown sandy sediments. The Nikolaos Fm. includes the lacustrine deposits which overlay the Nikiti Fm. and consists of alternated lenses or lenticular intercalations of clays, sands, sandstones and fresh-water marly limestones at the top. They can be correlated to the Triglia Fm. and Trilophos Fm. of western Chalkidiki, respectively. Several fossiliferous sites and spots have been found in the Nikiti region but two of them provided a rich mammal fauna; one of them gave also some bird and reptile remains. The excavations in the Nikiti region started in 1990 and they are divided in two periods: 1990–1998 (“old collection”) and 2004–2009 (“new collection”). Both collections include a large number of fossils and provide insights to the dating of the Neogene deposits as well as to the late Miocene biochronology and palaeoecology in this eastern Mediterranean area.