To evaluate the postoperative analgesic effect and postoperative nausea and vomiting (PONV) after using epidural low-dose morphine-soaked microfibrillar collagen sponge (MMCS), as compared with placebo.A prospective randomized double-blind placebo-controlled study was performed on patients under-going single-level posterior lumbar spinal decompression and instrumented fusion at the Department of Orthopedic Surgery, Siriraj Hospital, between August 2012 and December 2013. Patients were randomly allocated into two groups to receive either an epidural MMCS or an epidural normal saline-soaked microfibrillar collagen sponge (placebo). Intensity ofpain, PONV and total amount of morphine were recorded at 4, 24, 48, and 72 hours, postoperatively.The analgesic effect was enhanced significantly in the epidural MMCS group, as the amount ofmorphine used was statistically less than in the placebo group at 4 and 24 hours (p < 0.05).A single low-dose epidural MMCS is effectiveforpain control after posterior lumbar spinal surgery with a low incidence of PONV.