The aim of the present investigation was to determine the effect of pulsed plasma nitriding process on the wear behavior of an AISI 4140 steel. Wear tests were performed using a ball-on-disc configuration with a linear sliding speed of 0.1 m s(-1), 5 N load and 700 m sliding distance. The tests were carried out at room temperature in air, without lubrication, by employing CVD TiN coated balls of 6 mm in diameter. The surface morphology and topography of the wear scars of samples and balls have been determined by using both scanning electron microscopy and three-dimensional stylus profilometry. Different wear mechanisms were detected such as abrasion, adhesion and oxidational wear for the pairs under study. Results have showed an improved wear resistance of the nitrided samples compared to the AISI 4140 steel samples.