Electron spin resonance and infrared spectroscopic techniques have been used to examine the thermal and environmental deterioration of ivory from Nimrud, Iraq. It has been possible to ascertain the extent of ancient pyrolysis of the ivory with the former technique, and infrared spectroscopy has allowed an insight into the deterioration of the protein matrix of the ivory both in relation to, and independent from, thermal breakdown. Comparative spectroscopic studies of both ancient and modern ivory are also reported. The structural information obtained is discussed in the light of previously reported studies based upon chemical analyses.