A surgical instrument for performing a circular anastomosis is disclosed. The instrument is provided with sealing means to permit use during endoscopic procedures. The sealing means includes a first, O-ring seal disposed intermediate of a compression member, wherein the first seal is configured and dimensioned to at least partially contact an outer portion of the compression member and an inner portion of an outer tube. The second seal at least partially disposed proximal the first seal and has a first diameter portion, a second diameter portion and is disposed about the compression member. The compression member has at least one aperture which the second seal is adapted to engage.