OBJECTIVE: A prospective, randomized, controlled clinical study is performed to verify the effectiveness of epidural dexamethasone-soaked gelatin sponges to reduce postoperative pain following lumbar microdiscectomy. METHODS: Twenty-three patients (10 men and 13 women) undergoing lumbar microdiscectomy were included. Five pieces of gelatin sponge measuring 1 x 1 cm (Gelfoam; Pharmacia & Upjohn, Kalamazoo, MI, USA), soaked with either 5mg dexamethasone or an equal amount (2 mL) of saline, were left on the decompressed nerve root after unilateral hemilaminectomy, flavectomy and discectomy. RESULTS: Subjective visual analog scale(VAS) scores of leg pain in the dexamethasone group on the first, third and fifth postoperative days (2.5, 2.5, 1.7, respectively) were significantly lower than in the control group (5.0, 4.8, 3.6) ( P<0.05). No side effects related to the dexamethasone-soaked gelatin sponges were observed. CONCLUSION: The intraoperative application of dexamethasone-soaked gelatin sponges during lumbar microdiscectomy can provide effective postoperative analgesia without complications.