Six cases of acute postdiscectomy cauda equina syndrome (C.E.S.) following lumbar discectomy were reviewed retrospectively in a series of 2842 lumbar discectomies over a ten-year period. Five cases had coexisting bony spinal stenosis at the level of the disc protrusion. The bony spinal stenosis was not decompressed at the time of discectomy. Inadequate decompression played a role in the neurologic deterioration postoperation. The cause of the sixth case is unknown. Bowel and bladder recovery was good when the cauda equina decompressed early; sensory recovery was universally good, and motor recovery was poor if a severe deficit had developed before decompression. Careful review of the preoperative myelogram to rule out spinal stenosis and decompression of bony stenosis at discectomy are recommended for prevention of postoperative C.E.S. Urgent decompression of postoperative C.E.S. is advisable if compression of the cauda equina is confirmed radiographically.