Hypothesis: Hyaluronic acid (HA)-based bioresorbable membrane and 0.4% HA solution reduce intra-abdominal adhesion and abscess formation in a rat peritonitis model. Design: Randomized laboratory experiment. Setting: A university hospital. Interventions: In 72 male Wistar rats, a bacterial peritonitis was induced using the cecal ligation and puncture model. Animals were randomized to receive isotonic sodium chloride solution (group 1), HA- carboxymethylcellulose bioresorbable membrane (group 2), or 0.4% HA solution (group 3). Half of each group were killed at day 7 and half at day 21, and adhesions were scored in a blind fashion. The presence and sizes of intra- abdominal abscesses were noted. Cultures were taken for bacterial analysis. Main Outcome Measures: Intra-abdominal adhesions and abscesses. Results: The median severity of adhesions was significantly lower in group 3 compared with group 1 rats at day 7 (II [range, I-IV] vs IV [range, I-IV], respectively; P = .02) and at day 21 (II [range, I-III] vs IV [range, II-IV], respectively; P = .02). There was no significant difference between group 2 and group 1 rats on either day. At day 7, abscesses larger than 2 cm were found in 6 of 12 group 1 rats and in 4 of 12 group 2 rats, but in 0 of 11 group 3 rats (P = .01). At day 21, 0 of 11 group 3 rats had an intra-abdominal abscess, in contrast to 4 (33%) of 12 group i rats and 5 (45%) of 11 group 2 rats. All cultures of abscesses revealed polymicrobial flora. Conclusion: Adhesion and abscess formation are reduced using a 0.4% HA solution, and not HA- carboxymethylcellulose bioresorbable membrane, in a rat model of generalized bacterial peritonitis.