Histologic and mechanical properties of chromic gut and glycerin-treated chromic gut were evaluated. Zero gauges of both materials were implanted for 7 days to evaluate inflammatory response. No difference was found in the degree of inflammatory response. Scanning electron micrographs showed a more uniform surface for the glycerin-treated chromic gut. Regular chromic material was stronger in unknotted tensile strength and fracture load for all gauges. The 1-0 gauge glycerin-treated chromic gut stabilized with the knot configuration of 1 = 1 = 1 = 1; and the 1,2-0, and 3-0 gauges reached knot security at 1 = 1 = 1. The in vivo studies showed marked difference in the tensile strength of stable knots between the two materials. Only with five throws (1 = 1 = 1 = 1 = 1) did the strength of glycerin-treated chromic gut overlap that of regular chromic gut.