In this paper the barrier properties of a series of polyamides used for food packaging applications were analyzed. In particular, permeation of water through the investigated polyamides was studied and water diffusivity and solubility were evaluated as a function of water concentration. Water vapor sorption tests were performed at 25 o C and at several water vapor activities on the four samples investigated. The obtained values were related to the macromolecular chain modification deriving from the introduction of different comonomers.