Titanium and Ti – 6Al – 7Nb alloy biomaterials have become relatively popular for surgical implants. Plasma nitriding are commonly used for orthopaedic devices which are subjected to articulation and wear, to increase the surface hardness, and reduce the generation of wear debris. This paper aims to demonstrate the structural and elemental analysis of plasma nitrided titanium and titanium alloy. A Commercially pure titanium Cp Ti and Ti – 6Al – 7Nb alloy were surface modified using plasma nitriding in order to study its microstructural changes. DC glow discharge plasma nitriding was performed for different period of time (namely 5, 10, 15, 20, 25 and 30 hours). The glow discharge was occurred by applying 650 V between the two parallel electrodes under 3 mbar nitrogen gas pressures. To characterize the nature of the modified layers produced and to correlate with the corrosion behavior of these medical materials, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) was employed on the modified surfaces. The effect of sputtering process that can occur during the nitriding process on the surface roughness was studied using Atomic Force Microscopy (AFM). The results shows that as the nitriding time processed the N+ concentration increases comparing to the metal and alloy matrix elements. Also the SEM micrographs shows two effected zones of the nitriding in the modified surfaces and the thickness of each zone depend on the nitriding time. The AFM results show that the nitriding process leads to reduce the surface roughness.