Optimization of resin usage in blow molding necessitates the use of nonround or nonaxisymmetric die tooling. These die geometries are referred to as ＇＇ovalized.＇＇ The extrusion and inflation of parisons formed from nonaxisymmetric dies are complex because of the radial thickness dependency. Four die geometries are considered in this work; one axisymmetric and three nonaxisymmetric. The three nonaxisymmetric dies have one side set at a constant die gap (1.5 mm) and the side rotated 90-degrees from it, set at progressively increasing die gaps (2.0, 2.5, 3.5 mm). A methodology is presented for the measurement of the radial parison diameter and thickness swell profile for ovalized parisons. The methodology employs a simple mass balance approach between an axisymmetric part and the parison it was blown from. Experimental results are obtained for the radial parison diameter and thickness swell at two radial locations.