This report outlines results of an investigation of the composition of bone pyrolysis tar produced in Mongolia. The liquid product (tar) yield was low: similar to4.9%. The elemental composition of the tar was C: 73.3%, H: 10.1%, N: 11.3%, 0: 5.3%. Size-exclusion chromatograms signalled the presence of generally smaller mass material than coal tars and pitches, with a range from about 2000 U downwards. GC-MS showed the tar to be mainly composed of aliphatic material with nitrogen functionalities attached as nitriles, pyridines, pyrroles and amides. Pyridines and phenols turned up as only minor components. Probe-mass spectra also showed no significant aromatic features in this bone tar. Traditional bone tar contains pyridines and quinolines in larger quantities than found here and was used for medicinal purposes. It was presumably prepared by higher temperature pyrolysis than the present tar. The disposal of this tar is likely to present environmental problems. In the absence of more profitable uses, destruction of the oil by combustion with excess air may provide a reasonable alternative. (C) 2003 Elsevier Ltd. All rights reserved.