Available methods for postoperative adhesion prevention are insufficient. A previous study demonstrated that LM-200, a bioadhesive cellulose derivative was effective in reducing adhesions. Increasing the viscosity of a polymer solution enhances the tissue separating properties. Theoretically, a combination of sodium polyacrylate (PA) and LM-200 would give more viscous solutions than LM-200 alone, and thus be more efficacious. Therefore the efficacy of various combinations of LM-200 and PA was investigated. A lesion was created in the peritoneum of mice. The solutions to be tested, or saline, were given intraperitoneally. One week post-operatively, adhesion formation was quantified and expressed as a percentage of the original lesion covered with adhesions. PA (0.01 and 0.03 wt%) given separately did not differ in adhesion reducing effect from LM-200 (p = 0.3710 and 0.3481) but PA (0.1 wt%) resulted in significantly less adhesion formation (p = 0.0004). The effect of LM-200 increased significantly when adding PA (0.01 wt%) (p = 0.0007) or PA (0.03 wt%) (p < 0.0001). When adding PA (0.1 wt%) the effect was even more pronounced (p < 0.0001). The combination of a bioadhesive cellulose derivative and the polymer PA, was effective in reducing postoperative adhesion formation and a dose-dependent increase in efficacy was obtained compared to using the two components separately.