The resistance of three different types of absorbable suture materials was studied in three groups which simulated intrauterine conditions. In group I the sutures were incubated in the amnioallantoic cavity of chicken embryo (CE) and in group II in the fetal tissue of CE. For incubation of sutures in group III, human amniotic fluid collected during cesarean section operations in the thirty-eighth week of pregnancy was used. We discovered that chromic catgut had a lower resistance in fetal tissue than in fetal fluid (p less than 0.01), which could be an important point in the selection of fetal dermal sutures. In vitro incubation in human amniotic fluid did not effect the known rate of loss of chromic catgut, proglactin 910 and polydioxanone.