"Anomalous" or "doggy" Merino wool appears to be an increasing problem in Australian woolgrowing. The pattern of the ortho-para cortical differentiation of the straighter-fibred anomalous growth has been compared with that of normal wooL It was found that demarcations of ortho- and paracortex typical of much coarser fibres, may be present in the fine fibres of anomalous growth. In general, doggy wool is coarser than the normal flock mean and has a higher percentage occurrence of paracortex in the cross section.