OBJECTIVE: The peritoneal fluid cell responses to the available barriers used to prevent postoperative adhesions, oxidized regenerated cellulose (interceed) and expanded polytetrafluoroethylene (Gore-Tex Surgical Membrane), were compared. STUDY DESIGN: Oxidized regenerated cellulose and expanded polytetrafluoroethylene were inserted into the peritoneal cavity of mice and the peritoneal fluid cell number, differential cell count, morphologic type, adherence to plastic, and phorbol-12,13-myristate acetate-stimulated hydrogen peroxide production evaluated. Peritoneal fluid cell attachment to oxidized regenerated cellulose and expanded polytetrafluoroethylene was evaluated by electron microscopy. RESULTS: Oxidized regenerated cellulose promptly elicited increased numbers of large, morphologically activated peritoneal fluid macrophages that adhered more rapidly and produced more hydrogen peroxide than controls. Expanded polytetrafluoroethylene gradually increased the number of normal-appearing peritoneal fluid macrophages with increased hydrogen peroxide production but normal adherence. Macrophages rapidly attached to both materials in vivo, with oxidized regenerated cellulose being rapidly degraded. CONCLUSION: Oxidized regenerated cellulose, to a greater extent than expanded polytetrafluoroethylene, elicits an acute peritoneal fluid inflammatory exudate in the mouse, which may contribute to the oxidized regenerated cellulose-induced peritoneal injury and de novo adhesions observed in this model.