The first collection of fossils in the natural history museum was part of the donation of the Society of Sciences to the state in 1922. Since then it has grown by excavations, by donations and several acquisitions. The most important private collections added before 1985 to the historical collection of the museum were: X. deWael, E. de Muyser E., V. Ferrant, X. Leesberg, H. Reding, J. Robert., L. Senninger, P. Siegen, N. Laux, F. Heuertz,. More recent acquired collections meanly originate from the scientific collaborators of the MnhnL. Today the collections has about 70.000 fossils, half of it is recorded (20.000 records).

The predominant provenances of the fossils are the Eifel, Eislek and Ardennes for the Devonian species, the Lorraine, Gaume and Guttland for the Jurassic fossils. The Paris Basin stratigraphical area is fairly good represented, du to the collection of P. L. Maubeuge and the E. Pellat Collection of the UCL. The main systematic groups in number of pieces and in degree of determinations, are Jurassic cephalopods, gastropods and bivalves so as devonian brachiopods and trilobites. The geological formations with complete fossil faunas are the Luxembourg Sandstone, the Sonninia-layers, the minette iron formation and the Dogger limestone. A nice collection of fossil woods from G. Janssen and the leafs from US coal Measures should be mentioned in Paleobotaniocal topics.