The Kostolac mammoth was discovered in 2009 in Pleistocene deposits adjacent to the Drmno open-cast lignite mine in the Serbian Danube Basin. On the basis of cranial and dental features, the individual is identified as the so-called ‘steppe’ mammoth, Mammuthus trogontherii. The remains are those of an old male of estimated age around 62 years, and comprise one of the most complete and best-preserved known skeletons of this species, and the first from the region. Skeletal height is estimated as around four metres, and body mass 9.5 t. The excellent preservation of the skeleton provides new information about the osteology of M. trogontherii, an evolutionary intermediate between the better-known ancestral mammoth Mammuthus meridionalis and woolly mammoth Mammuthus primigenius. The find is also remarkable for the articulated condition of the skeleton, the animal occupying a crouching posture which is probably little-altered from its original death position. This and the depositional environment of the skeleton, a broad, fast-flowing river, suggest that the animal died in relatively shallow water and was very rapidly buried in river sediments. Based on the known European record of typical (large-sized) M. trogontherii of this kind, the age of the Kostolac skeleton and its enclosing sediments is between 1.0 and 0.4 Ma.