Nonlinear stress-strain behavior of the elastomer foams of high porosity is investigated in several types of biaxial tension, and uniaxial tension and compression. The values of Poisson's ratio for the open-and closed-cell foams are estimated to be about 0.24 almost independently of the imposed tensile strain, indicating that the foams undergo finite volume increase under tension. Unequal biaxial tensile experiments reveal no explicit cross-effect of strains between different axes in the elastomer foams: The deduced strain energy density function (W) has no appreciable contribution from the term of I-2 which is the second invariant of deformation gradient tensor representing the explicit cross-effect of strains, while in general W for conventional non-cellular elastomers involves finite contributions from I-2-term. No explicit cross-effect of strains result in a unique feature in biaxial tensile behavior that the effect of the strain in one direction on the stress in the other direction is considerably small. These features in tensile behavior are commonly observed for the open-and closed-cell foams. In contrast, the cell type has a pronounced effect on the compression behavior accompanying the buckling and collapsing processes of the cells, as observed in earlier studies. The stress-strain relations in compression accompanying the cell buckling are markedly different from the expectation of W obtained from the data of biaxial and uniaxial tension where the cell bucking is not possible. (C) 2015 Elsevier Ltd. All rights reserved.