The crack opening displacement (COD) testing method was used to evaluate the anisotropy of the fracture behaviour of a C-Mn (A36) structural steel. The values of COD at initiation, at maximum load and the resistance curve were obtained. The differences in fracture behaviour of the differently oriented samples was attributed to the orientation of the inclusion and the banding of the microstructure. Fractographic and metallographic analyses showed that there is a strong influence of banding on the fracture behaviour of the steel. 7 refs., 9 figs., 3 tabs.