This experimental study has shown that there is no difference in calcification on catgut and polyglycolic acid suture loops within the sterile and infected rat bladder. The presence of an experimentally induced infection reduces the time both catgut and polyglycolic acid sutures remain attached to the bladder wall. Polyglycolic acid sutures can nevertheless be recommended for routine use in the urinary tract whenever an absorbable suture is required in view of its greater strength, reliability and remarkable lack of inflammatory tissue reaction.