A 51-year old patient with congenital basal cell naevus syndrome was treated with etretinate (50-100 mg/daily) over a period of 5 years (cumulative dose 110 g). Clinically he developed a stiff back with pronounced disability of both hips. Radiologically, axial involvement of the spine with severe diffuse idiopathic skeletal hyperostosis especially of the lumbar spine, and ossifications of both hips were documented. Rheumatological implications of long-term therapy with etretinate are discussed.