Abstract Purpose of study: This study directly compares an antifibrotic agent (Adcon-L gel; Gliatech, Cleveland, PH), an expanded membrane (poultetrafluoroethylene Preclude spinal membrane [Gore & Associates, Inc. Flagstaff, AZ]) absorbable collagen sponge (ACS; Helistat, Integra Life Sciences Corporation, Plainsboro, NJ) and the more classically practiced grafting with fat for inhibition of the postlaminectomy scar. Methods used: Twenty-five adult female Sprague-Dawley rats weighing 250 to 300 g underwent complete bilateral laminectomy at the L2 and L5 vertebral levels (two sites per rat). Treatments applied after laminectomy were Adcon-L gel, Preclude spinal membrane and ACS. Laminectomy-only sites with no added treatment served as controls. The barrier sheets (Preclude and ACS) were laid across while the gel (Adcon-L) was injected onto the surface of the exposed dura and nerve roots. The rats were sacrificed 180 days postoperatively and the lumbar spines excised en bloc, fixed and decalcified. Sections stained with hemotoxylin and eosin underwent qualitative histologic analysis by investigators blinded to the treatments. An adjacent area of scar was quantified and standardized to canal yielding a scar-to-canal ratio. Analysis of variance was applied to these data. of findings: A total of 36 sites were processed for histologic analysis. The least amount of fibrous adhesions as well as extradural scarring was observed in sites treated with Adcon-L. Scarring in sites treated with Adcon-L was significantly less then in sites treated with Preclude (p<.05) and laminectomy alone (p<.009). In comparison to laminectomy only, a significant decrease in scarring was also observed for sites treated with fat. There was no difference between Preclude or ACS versus laminectomy alone. Preclude membrane, a nonabsorbable material, was well visualized histologically, and in many sites the position was not maintained. If the barrier material had migrated from the laminectomy site, scarring was not affected (Fig. 1) . Relationship between findings and existing knowledge: The formation of the dense, fibrous laminectomy membrane after lumbar surgery may be a strong indicator of persistent pain, morbidity, slow recovery and poor outcomes. Because this membrane is adherent to the dura and overlying muscles, it increases the technical difficulty of dissection in subsequent surgical procedures. Several antifibrotic agents as well as barrier materials have been investigated as techniques for the inhibition or neutralization of postlaminectomy fibrous scar tissue formation. Overall significance of findings: Sites treated separately with Adcon-L or fat exhibited the least amount of scar. Fibrous tissue was decreased in both these sites when compared with surgery alone. The greatest amount of scar was typically observed in sites treated with ACS or for untreated laminectomy sites. The findings from this pilot study indicate potential use of antifibrotics or fat independently in the reduction of postlaminectomy scar tissue formation and warrant consideration for future studies. Disclosures: Device or drug: Preclude. Status: approved. Device or drug: Adcon-L. Status: approved. Device or drug: absorbable collagen sponge. Status: approved. Conflict of interest: No conflicts.