Shot peening (SP) was carried out in order to improve the fatigue life of an austempered ductile iron alloyed with copper and nickel austenitised at 900°C for 2h and austempered at 360°C for 1h. The optimal peening intensity using S330 steel shot, was found to be 0.38mmA producing residual compressive stresses with a maximum of approximately 1000MPa at the surface. The microhardness at the surface was increased by SP from 370 to 535HV. The fully reversed fatigue tests of SP-specimens showed a 61% increase in fatigue life over that of polished samples. The improvement in fatigue life is explained by the compressive residual stresses in the near surface shifting crack initiation to sub-surface. Fractography analysis showed multiple crack nucleation sites at the surface for the polished specimens, while SP-specimens showed sub-surface crack nucleation. In addition, a mixed fracture mode was also identified, with the graphite nodules and copper islands affecting crack propagation.