Grading of dysplasia is demanded almost daily from most diagnostically active pathologists. It is also notoriously subjective and lacks intra- and inter-observer reproducibility. This is partly due to the lack of validated morphological criteria, upon which pathologists have reached consensus. It is largely due to the biological nature of the evolution of dysplasia, not in discrete steps but as a continuum. Better morphological definition, but also fundamental research into the nature of the process, is necessary to resolve this issue