This study tested the reaction of a periarticular tissue to implanted pericardial membrane, substituting a segment of patellar ligament. Bovine pericardium was chemically purified and cross-linked with monomeric glutaraldehyde under pH, temperature and time conditions minimizing the polymerization of the cross-linking agent. Eight rats had both knee joint patellar ligaments excised. One side served as a control (simple suture), the other dissected ligament was replaced with a strip of pericardium. After 18 days and 12 weeks the dissected ligaments were analyzed by morphological methods. An unexpected fast ingrowth of cells and vessels was observed at 18 days. At 12 weeks new collagen deposits within pericardial patch were seen with striking biodegradation of the implant. Thus, using a new method of cross-linking the collagenous matrix with glutaraldehyde we see no evidence of glutaraldehyde cytotoxicity, as documented by our previous work.