The specificity of conventional radiography in assessing canine hyperadrenocorticism was evaluated by comparing the incidence of related radiographic findings in 24 hyperadrenocorticoid, 15 diabetic and 20 hypothyroid dogs. Hyperadrenocorticoid dogs showed significantly more perihilar bronchial mineralisation than other groups. There was no significant variation between the disease groups with respect to obesity, hepatomegaly, contour of the caudoventral hepatic margin, peripheral bronchial mineralisation or osteopenia. Adrenal mineralisation and calcinosis cutis were rare findings observed only in hyperadrenocorticoid dogs. The effect of obesity on the radiographic appearance of bone was studied using a dissected lumbar spine from a canine cadaver. An osteopenic effect could be demonstrated by superimposition of a 10 cm-thick fat block. The low specificity of almost all common signs in canine hyperadrenocorticism and the low incidence of characteristic findings demonstrate the limited potential of radiography in assessing this condition. Radiographic assessment of bone density is unreliable because of artefactual osteopenic effects of high kVp settings necessary in obese dogs.