Several composite laminate structures with different stacking sequences were manufactured to study how the special orientation of the fibers can influence the porosity distribution in the material. Different amounts of porosity were introduced into the laminate during autoclave curing through the application of pressures that differed from the prescribed one. All of the obtained structures were analyzed by ultrasonic inspection to measure the attenuation undergone by the signal through crossing within the material. Subsequently, the attenuation variations were associated with the induced porosity. The obtained results were corroborated by an estimation of the percentage of porosity introduced into the composites structures through the application of a standard method for density measurement. The results prove that there are stacking sequences much more subject to trap air with the consequent formation of the porosity. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3583-3589, 2011