Abstract. Using archival data from the Hubble Space Telescope, we study the quantitative morphological evolution of spectroscopically confirmed bright galaxies in the core regions of nine clusters ranging in redshift from z = 0.31 to 0.84. We use morphological parameters derived from two-dimensional bulge-disc decomposition to study the evolution. We find an increase in the mean bulge-to-total luminosity ratio as the Universe evolves. We also find a corresponding increase in the fraction of early-type galaxies and in the mean Sérsic index. We discuss these results and their implications to physical mechanisms for evolution of galaxy morphology.