The method of N-terminal analysis has been applied to the protein fractions of beef to detect proteolysis on storage a t low or high temperature. Parallel studies have been made on the histology, non-protein nitrogen and free amino-acids, and on the extractability and electrophoresis of the structural proteins. While definite small increases in free amino-acids occur, increases in N-terminal groups were negligible. Other results give no evidence of proteolysis. It is concluded that proteolysis is not a significant factor in the tenderising of beef by ageing.