Capillarity functionals are parameter invariant functionals defined on classes of two-dimensional parametric surfaces in R 3 as the sum of the area integral and an anisotropic term of suitable form. In the class of parametric surfaces with the topological type of S 2 and with fixed volume, extremals of capillarity functionals are surfaces whose mean curvature is prescribed up to a constant. For a certain class of anisotropies vanishing at infinity, we prove existence and nonexistence of volumeconstrained, S 2 -type, minimal surfaces for the corresponding capillarity functionals. Moreover, in some cases, we show existence of extremals for the full isoperimetric inequality.