yWe studied the swelling and elastic behavior of chemically cross-linked [2-(methacryloyloxy)-ethyltrimethylammonium chloride-2-(acrylamido)-3-ethylpropanesulfonate] polyampholyte gels in equilibrium with saline solutions. The net charge of the polymer network and the ionic strength of the swelling solvent are crucial parameters governing the properties of the gels. The swelling equilibrium behavior of gels with a strong charge imbalance was analogous to polyelectrolyte systems (monotonic decrease of swelling ratio with rising salt concentration). Globally neutral gels showed an antipolyelectrolyte behavior (collapse at low ionic strength and monotonic increase of swelling ratio with rising salt concentration). Weakly unbalanced polyampholyte gels showed a characteristic minimum in their swelling curves, the same gel reaching the same equilibrium volume in two different ionic conditions. The internal structure was imaged using differential interference contrast microscopy and revealed that morphological modifications of the gel structure accompany volume variations. The evolution of the elastic modulus of polyampholyte gels at equilibrium is quite complex, because the same sample can behave like a polyelectrolyte in low ionic strength conditions and as a balanced polyampholyte at high ionic strength, Thus a polyampholyte gel can reach the same swelling ratio at equilibrium for two different ionic strengths, but is then characterized by two different values of the shear modulus.