The determination of levels of porosity is important in the engineering uses of graphite fiber/polymer matrix composites, since the interlaminar shear strength can be greatly reduced by excessive porosity [1). Research in making nondestructive evaluations using ultrasonics as the probing energy has taken many directions. Hsu [2) has successfully modeled the frequency dependent attenuation to predict porosity levels in composites. Kline [3) has extended the work of Hashsin and Rosen [4) to determine the porosity and fiber volume fraction of composites by solving for the elastic coefficients of the composite structure. The propagation of leaky Lamb waves [5) has also been used to model porosity levels.