This is a comparative study of the disintegration of absorbable sutures when incubated in human gastric juice, bile, pancreatic juice, and their mixture. Plain catgut rapidly lost its strength in each of these digestive fluids. Chromic catgut was susceptible to digestion although it retained most of its strength in bile for two weeks. Synthetic absorbable sutures, polyglycolic acid or its derivatives (Dexon "S", Dexon Plus, and Maxon), maintained most of their strength for 2 weeks, disintegrating only after 5 to 8 weeks. Controls of saline or human plasma had little demonstrable effect. As a further control, silk maintained its strength under each exposure. Although catgut is widely used, the study suggests that it disintegrates too rapidly, at least under the conditions tested, to be appropriate for alimentary tract surgery, whereas the synthetic sutures maintained their integrity rather well for the 2 to 3 weeks needed for visceral wound healing. The data suggest that slowly absorbed synthetic sutures may be particularly useful in pancreatic or biliary anastomoses where a single layer is preferable and where a nonabsorbable suture offers inherent disadvantages.