Biodegradable single-phase cohesive hydrogels useful, e.g., for the formulation of viscosupplementation compositions or compositions for filling wrinkles, contain a homogeneous blend of x polymers, which may be identical or different, crosslinked prior to the interpenetration thereof by mixing in the form of a single-phase hydrogel, wherein such crosslinked polymers are insoluble in water and miscible with one another, and x ranges from 2 to 5； in one embodiment, the hydrogels are such that the x polymers have identical or different degrees of crosslinking, at least one of the x polymers having a degree of crosslinking x1 and at least one of the x polymers having a degree of crosslinking x2, with x1 being greater than or equal to x2.
