The aim of this investigations was to characterize and compare fractographic features of two polymers: polyamide (PA6) and polyoxymethylene (POM) as a function of their microstructure. The microstructure of the basic polymers was changed by the addition (by injection) of a thermoplastic elastomer (ionomeric ethylene copolymer-Surlyn). It was observed that the used modifier strongly affected the mechanical properties and fracture topography of the investigated polymers. In addition, the fracture mechanism of the polymers (based on the observed fracture features, sections and fracture surfaces obtained at room and liquid nitrogen temperature) was investigated. (C) 2003 Elsevier Science B.V. All rights reserved.