Transmission electron microscopy (TEM) was used to examine the morphology of extruded thermoplastic starch/poly(ethylene-vinyl alcohol) (EVOH) blends. Both the starch and EVOH polymers were found to be very beam sensitive : the maximum allowable beam dosages for the crystalline fraction of both components are estimated at less than 3.5 x 10(-3) C cm(-2) at 200 kV and room temperature. In addition, both polymers experienced significant mass thickness contrast variations which at moderate beam dosage ( > 6.0 x 10(-3) C cm(-2)) led to contrast-reversal of images of the blend morphology. Noting the effect of the electron beam on the materials, low dose techniques were used with conventional TEM to reliably image the blends. For as-processed starch/EVOH blends, EVOH was observed to be the matrix component even at very high starch concentrations (up to 70%). Domain sizes of starch were observed to range from less than 0.1 mu m to greater than 3 mu m indicating that all of the starches became destructurized during the preparation of the blends. Variation in the blend structure was also observed at similar starch compositions (50%) for the three corn starch types. An analysis of contrast differences in blends containing Waxy Maize, Native Corn, and high amylose Hylon VII starches with EVOH suggested increasing miscibility with increasing amylose content in the starch component. Finally, structural gradients in thermoplastically formed articles (e.g. a starch/EVOH melt-spun fibre) were observed.