Teeth are increasingly utilized as a source of nuclear DNA to aid identification of human remains. DNA extraction and the results of genetic analysis from these tissues are extremely variable and to some extent unpredictable. This study examines the availability of nuclear DNA in different areas of the dental hard tissues and explores the extent and nature of the variation within and between individuals. Results of this study indicate that nuclear DNA is available in widely variable quantities in dentine and cementum. This variation exists within teeth and between teeth, even between comparable teeth from the same individual. The quantity of DNA available in dentine is affected by age and dental disease, whereas that in cementum is not. Forensically useful genetic profiles were obtained from as little as 20 mg of tooth powder, thus avoiding the necessity for complete destruction of the tooth. A better understanding of why there is more DNA in one tooth tissue or region compared with another, and of the effects of disease and age, will aid in the selection of which tooth and tissue to sample and will increase the validity of the use of teeth as a source of nuclear DNA for human identification. ; Denice Higgins, John Kaidonis, Jeremy Austin, Grant Townsend, Helen James and Toby Hughes