- The invention relates to an implantable surgical ring designed to form a closed loop for squeezing a biological part in order to modify the cross section of flow of said part, said ring comprising a flexible hose (2) which is bent round upon itself and is made of an elastomer material by one-piece moulding, said ring being characterized in that said hose (2) defines at least two adjacent inflation chambers (4, 5), each having in transverse cross section a domed shape projecting into the loop, said chambers (4, 5) being designed to receive an inflation fluid, and said hose (2) also comprising a partition designed to prevent a transfer of inflation fluid between the two chambers (4, 5) along at least a part of their length. -Surgical rings.