Radiographic examination of the metacarpus and metatarsus from 333 fallow deer revealed a high incidence of animals with an angular deviation of at least one epiphysis. The incidence in males (59 per cent) was significantly higher than that in females (21 per cent). The cloven hoof is bent laterally and a deviation of up to 23 degrees was recorded. A deer with one deformed foot is equally likely to have 2, 3 or 4 deformed feet and no bone is more susceptible than others. Fusion of the epiphyses commenced at about 16 months and was complete by about 32 months, and the angular deformity occurred before this age. The incidence increases with increasing age in deer whose epiphyses have not yet fused. Other radiographic changes noted were growth plate deformities in young deer of 8 to 12 months of age and bowing of the shaft of the cannon bone in some older animals. It is suggested that the following sequence of events could involve all 3 defects and provide an explanation for the gross angular deviation of the foot seen in some deer. First, a defect in the process of calcification as a result of a nutritional deficiency causes hypertrophy of the cartilage of the growth plate, with local epiphyseal damage. Second, a compression or a breakdown of the cartilage of the cannon bone, particularly if on one side only, causes angular deviation of the epiphysis. Subsequent ossification leads to fusion of the diaphysis with the epiphysis at an abnormal angle. Third, the defect in calcification of the diaphysis leads to a weakness in the bone which, if stressed, becomes deformed and, after subsequent ossification, is seen as a bowing of the cannon bone.