Lateral lumbar disc herniations (L.D.H.) develop in the foramen, and compress the nerve root against the overlying vertebral pedicle. In our study of L.D.H. from the clinical, radiographical, and therapeutical aspects, we reviewed 23 cases selected from the 590 patients treated for discal herniation from 1984 to 1987. The frequency of L.D.H. in this series was 3,8 per cent. The clinical pattern brings out some suggestive signs of L.D.H. (frequency of cruralgia, a seldom very positive Lasegue's test, the paucity of spinal signs, non impulsive pain). Saccoradiculography and discography rarely evidenced the L.D.H.. The T.D.M. was the investigation of choice on condition that it was correctly used. When the image was doubtful, disco-CT confirmation should be proceeded too. This latter method of investigation enabled the possibility of sequestration to be explored. 14 patients were treated by chemonucleolysis, with 9 successful outcomes. The 5 failures were cases where chemonucleolysis should not have been indicated, mainly due to associated osseous stenosis. 9 patients underwent immediate surgery with good results in each case.