The enzymic hydrolysis and solubilisation of the three meat protein fractions have been investigated in order to elucidate some aspects of the hydrolysis of whole beef protein. Much of the water-soluble sarcoplasmic protein fraction was insolubilised on heating for 25 min at 60°C. While most of this insoluble protein was easily resolubilised enzymically, some of it remained insoluble after 5 hours' hydrolysis. Solubilisation of connective tissue by Alcalase after a 3 h reaction increased markedly from 23% at 55°C to 99% at 60°C. This explains the high optimum temperature for solubilisation of whole beef by Alcalase. A significant portion of myofibrillar tissue remained insoluble after 3 hours' reaction. indicating that the majority of the insoluble solids remaining after whole meat hydrolysis at 60°C derived from myofibrillar tissue. There was good agreement between an experimental reaction progress curve for whole beef hydrolysis and one estimated from progress curves for hydrolysis of the three meat protein fractions.