In this article we present an opto‐thermo‐mechanical characterization of isotactic polypropylene monofilament during failure by fracture. The digital photoelasticity, the two‐beam Pluta polarising interference microscope and the computed tomography are used to provide quantitative data and visual models of the fracture regions of isotactic polypropylene fibers suffering failure by fracture at different thermal and mechanical conditions. Birefringence values and the intrinsic stress‐anisotropy are measured at the fracture surface. 3D models of the fracture regions are reconstructed. Photoelastic patterns and two‐beam interferograms are included for illustration. Three different techniques are used for visualization the failure by fracture of isotactic polypropylene fibers. Systematic discussion of fracture mechanism is given. It concluded that the fiber core layers would fail before their outer layers.