Contact fatigue properties of austempered nodular iron transformed at 230 °C to Rc 45-47 were evaluated using roller contact fatigue tests. At a given load, contact fatigue life of the austempered iron was 35 to 45 pct lower than carburized steel. Shot peening, performed using 1.168-mm diameter Rc 45-55 cast steel balls to Almen strip intensity of 0.006 to 0.008 C, was not beneficial. An increase in the surface compressive residual stress introduced by shot peening was accompanied by surface roughening which lowered the fatigue life by detrimentally influencing the EHD film thickness. Stress induced white etching areas well known to develop in high carbon martensite were found to develop in bainitic microstructure also.