Nitriding of steels, using plasma environments has been practiced for many years. A lot of efforts have been put on developing new methods, such as plasma immersion ion implantation (PI3) and radio frequency (RF) plasma nitriding, for mass transfer of nitrogen into the surface of the workpiece. This article presents the results obtained from an in depth investigation of the surface morphology of the treated samples, carried out using an ATOMIC FORCE microscope ((AFM)). Samples from microalloyed steel were treated by both methods for 5 hours at different temperatures ranging from 350 to 550 °C in 75% N2 -25% H2 atmospheres. It has been found that the surface of the samples treated by PI3 technique, although having morefavorable properties, were rougher than the surfaces treated by RF plasma nitriding.