A collagen-coated Vicryl mesh bioprosthesis was used to repair a 4 x 4 cm full-thickness abdominal wall defect, created in experimental rats. The tensile strength of the repair at 6 months reached 70% of the original abdominal wall. Implant collagen could not be differentiated from host collagen after 2 weeks. The increase in collagen content of the repair was responsible for the increasing tensile strength of the wound with time. All histological sections showed good tolerance of the implant. These results support the use of collagen Vicryl membrane to repair large abdominal wall defects. Clinical trials are indicated.