The authors report 8 cases of patients with synovial cysts (3 cases) or diverticuli (5 cases) of the lumbar joints, compressing the sciatic roots. They describe the radiological aspects of the two sides of the degenerative pathology of the posterior articular processes, which are relatively unrecognized (14 cases in the literature). They insist on the advantage of saccoradiculography which is the only test to be able to demonstrate dynamic alterations in relation with diverticuli, if performed in a standing position. The authors show the advantage of tomodensitometry which supports the diagnosis of cyst in the presence of a fibrous wall image. They emphasize the value of the arthrography of the posterior joint; it presents a diagnostic role by visualizing the cavities, and a therapeutic role by permitting the injection in situ of steroids and/or local anesthetics.