The effects of instilling methylprednisolone acetate (MP) (Depo-Medrol) onto the exposed nerve root during a unilateral lumbar laminotomy (either L4 or L5) for disc excision was studied in 43 patients (primary: 35; repeated procedure: 8). The results were compared with two similarly matched control groups without the steroid drug. All 86 patients preoperatively experienced radicular pain to the calf, and were operated on by one surgeon. Four parameters, studied during the postoperative hospital stay, were compared between the control and MP series. The MP (primary/repeat) groups' (a) stay was reduced by 37/40%, respectively; (b) need for strong narcotic drugs was decreased by 64/70%; (c) need for milder pain medication was decreased by 49/72%; and (d) need for spasm medication was reduced by 77/59%. The paired t test indicated that there is a statistical difference between the MP and control groups' results because of the use of MP, with confidence levels of 0.9927-0.9999 in the primary group, and 0.9806-0.9913 for three of the four parameters in the repeat group. Intraoperative application of epidural steroid drugs such as MP, in a unilateral low-lumbar discectomy, leads to a shorter hospital stay because of less pain and spasm.