The cystometry had been performed in 28 cases of H.L.D. and 1 case of unstable lumbar spine due to spondylolysis from January 1974 to September. Among them, 24 cases were checked cystometry again after one week of postoperative period. We obtained the results as follows: 1. Preoperative cystometrograms were revealed that 21 cases were bladder hypofunction,3 cases were bladder irritability, and 5 cases were normal. 2. The postoperative cystometrograms were revealed that were improved in 3 cases, unchanged in 19 cases, and worsened in 2 cases. 3. It is likely that the bladder hypofunction is related to the severity of radiating pain rather than the severity of myelographic findings, the direction and the level of disc herniation.