31 cases of 27 patients with symptomatic disc herniation were treated with automated percutaneous lumbar dicsectomy (APLD) from January 1989 to March 1992 in Hangang Sacred Heart Hospital. Among these cases, 23 cases of L4-5 disc herniation were treated randomly with either of curved or straight needle. Authors compared results of curved needle with straight one. The following results were obtained. 1. Among 13 cases of straight needle used in L4-5, 9 cases revealed good result (71%). 2. Among 10 cases of curved needle used in L4-5, 8 cases revealed good result (80%). 3. Overall successful rate of straight needle and curved needle used in L4-5 is 73%. 4. Amount of removed disc of straight needle used in L4-5 is 2.2gm to 7.5gm (average; 4.6gm). 5. Amount of removed disc of curved needle used in L4-5 is 3.5gm to 8mg (average; 5.lgm).