A revision of the ammonites from Maastricht and adjacent parts of Limburg and Liège based on the BINKHORST Collection in the Museum für Naturkunde, Berlin, the collections of the Institut Royal des Sciences naturelles de Belgique, Brussels, (including material described by A. DE GROSSOUVRE in 1908) and the Natuurhistorisch Museum, Maastricht, revealed the following sequence of faunas. The youngest Campanian ammonite from the Vaals Formation is a specimen of Hopliloplacenticeras marroti (COQUAND, 1859) from Vijlen, Cotessen (Zuid-Limburg, The Netherlands); this is a typical lower Upper Campanian species. The Zeven Wegen Chalk yields Baculites at several localities and upper Upper Campanian Hopliloplacenticeras coesfeldiense (SCHLUETER, 1867) and Trachyscaphites spiniger (SCHLUETER, 1872) at Vijlenerbosch (Zuid-Limburg, The Netherlands): these are Bostrychoceras polyplocum Zone species. An unspecified horizon within the Gulpen Formation of Schneeberg, north of Vaals yields the lower Lower Maastrichtian Acanthoscaphites tridens (KNER, 1848); the same species occurs at Vaals. No ammonites were seen from the Beutenaken Chalk, but the Vijlen Chalk yields phosphatised and unphosphatised Baculites at a number of localities, Hoploscaphites tenuistriatus (KNER, 1848) at Mesch (Zuid-Limburg, The Netherlands), and there is a record of Pachydiscus sp. from Hallembaye, Liège. No ammonites were seen from the Lixhe or Lanaye Chalks. The base of the Valkenburg Chalk yields phosphatised Baculites anceps LAMARCK, 1822, and phosphatised Baculites sp. at the Blankenberg Quarry, Cadier en Keer (Zuid-Limburg, The Netherlands). No ammonites were seen from the Gronsveld, Schiepersberg or Emael Chalks. Ammonites known to be from the Nekum Chalk, mostly from the environs of Maastricht, are Anapachydiscus fresvillensis (SEUNES, 1890). Diplomoceras cylindraceum (DEFRANCE, 1816), Baculites vertebralis LAMARCK, 1801, B. anceps LAMARCK, 1822 and Hoploscaphites constrictus (J. SOWERBY. 1817). There are two records of Sphenodiscus binkhorsti ...