The influence of ethylene oxide gas treatment on the in vitro degradation behavior of noncrosslinked, glutaraldehyde crosslinked or hexamethylene diisocyanate crosslinked dermal sheep collagen (DSC) using bacterial collagenase is described. The results obtained were compared with the degradation behavior of either nonsterilized or γ-sterilized DSC. Upon ethylene oxide sterilization, reaction of ethylene oxide with the free amine groups of DSC occurred, which resulted in a decreased helix stability, as indicated by a lowering of the shrinkage temperature of all three types of DSC. Except for the low strain modulus the mechanical properties of the ethylene oxide sterilized materials were not significantly altered. γ-Sterilization induced chain scission in all three types of DSC, resulting in a decrease of both the tensile strength and the high strain modulus of noncrosslinked and crosslinked DSC. When exposed to a solution of bacterial collagenase, ethylene oxide sterilized materials had a lower rate of degradation compared with nonsterilized DSC. This has been explained by a reduced adsorption of the collagenase onto the collagen matrix as a result of the introduction of pendant N-2-hydroxy ethyl groups.