Study of the fracture behavior of annealed 1045 steel under quasi-static conditions at strain rates corresponding to epsilon congruent 10** minus **3 s** minus **1 (equivalent to K congruent 1 MPa ROOT m/s) and under dynamic loading rates corresponding to epsilon in excess of 10**3 s** minus **1 (K equals 10**6 MPa ROOT m/s) was undertaken. The dynamic fracture tests were performed using a Split Hopkinson Bar system. Furthermore, the fractured specimens were examined in a scanning electron microscope to measure the stretch zone width, stable crack growth and presence and density of dimples and inclusions as well as the size of facets. The transition from a predominantly ductile behavior at an almost cleavage fracture was identified as a function of strain rate. A quantitative relationship characterizing the variation of the stretch zone width with strain rate is given.