The authors present 12 cases of symptomatic acquired narrowing of the lumbar canal (with multiple nerve root involvement) in patients suffering from typical vertebral hyperostosis. In each case, the lesion was transverse stenosis due to hypertrophy of the articular apophyses of the last three lumbar vertebrae (posteromedial apophyses). Amongst the radiological abnormalities detected, especially with the aid of the C.T. scan in 6 cases, the authors stress the frequency of irregular bony proliferations on the non-articular surface of the articular apophyses and the ossification of the ligamenta flava, which has already been observed in the thoracic region in cases of vertebral hyperostosis.