The Dubois Collection is a very important collection of fossil mammals from Java and Sumatra in the Museum of Natural History in Leiden. The fossils were collected by Eugene Dubois between 1887 and 1900. Some information on Dubois and his motives to search for fossils in Indonesia is given. Then the human fossils from Trinil are discussed. At this locality Dubois discovered a tooth, a skull fragment and a left femur of Pithecanthropus erectus. His interpretation of these finds was heavily criticized at that time. After a short discussion of the position of Homo erectus in the human phylogeny, the author makes some remarks on the reconstruction of the outward appearance and on the ecology of Homo erectus.