The use of dentition as an indicator of age has been accepted for many years, particularly in the equine, although as yet, dentition as a means of age determination has never been used in cattle in commercial grading situations. The age of an animal at slaughter is generally believed to be inversely related to meat tenderness. Other aspects of meat quality have also been found to be affected by age, particularly in young bulls. These include flavour, juiciness, colour of lean and firmness. It has long been acknowledged that the greater stress susceptibility of bulls (who get more aggressive with increasing age) is the reason for the higher incidence of dark cutting in bull beef. The supply of older bulls to the food chain, may, therefore, be deleterious to meat quality and may be contributing to the poor reputation of bull beef. The objective of the present study was to develop a method for predicting chronological age at slaughter from the dentition of Aberdeen Angus x and Charolais x bulls. The experimental design allowed the effects of breed and diet to be assessed.