The peptide and casein breakdown products of enzyme accelerated and normal Cheddar cheese were monitored during ripening using reverse phase high performance liquid chromatography (RPHPLC) and polyacrylamide gel electrophoresis (PAGE). In contrast to PAGE analysis, the water soluble nitrogen fraction (WSNF) analysed by reverse phase chromatography exhibited more significant differences in pattern. The size of one band detected by reverse phase chromatography related well to Cheddar flavour intensity.