A variety of suture materials are available for use in urologic surgery. Urologists have relied on absorbable suture materials which provide transient strength in anticipation that healing will occur before the suture is absorbed. Absorbable sutures thus decrease the chance of stone formation, known to occur on suture material in direct contact with the urinary stream. This report compares the breaking strength retention of polydioxanone (PDS) suture and chronic surgical gut after in vivo residence in the urinary bladder and subcutaneous tissue of the dog.