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Microstructural effects on the fractality of cracks in steels at lowtemperatures have been investigated. The fractal analysis of fracture surfaces wasconducted employing broken three-point bend test samples of Ni-Cr steel with twostates of ferrite microstructure containing fine carbides. Alternation of fractaldimension in the direction of the crack propagation corresponds to characteristicregions ahead of sharp crack tip controlled by different fracture micromechanisms. Inthe ductile damage region the fractal dimension attains its maximum. In the brittlefracture region the fractal dimension is minimal and it does not change too much withincreasing distance from the initial crack tip. Competing effects of the transgranularand intergranular brittle failure can cause growth of surface roughness and its fractaldimension. The fracture toughness of the Ni-Cr steel tested in the transition region isinversely proportional to differences of fractal dimension in stable crack propagationarea and in the area of unstable brittle fracture.