Microscopical sections from 50 colorectal adenocarcinomas were examined to test the representativity of routine sections with regard to histological grade. Point-counting of drawings of microscopical fields from randomly selected parts of whole-tumour specimens formed the basis for estimates of volumetric relationships between parts of the tumours exhibiting well, moderately and poorly differentiated glands. An overall histological grade was assigned to each tumour, and was compared with the grade obtained by examining a limited number of routine sections from the same tumour. It is concluded that if superficial and deep parts of the tumours are included, and provided that the sections measure at least 2-3 cm, colorectal adenocarcinomas may be graded with sufficient accuracy on the basis of one or two routine sections.