The present work is concerned with microstructural changes brought about by ion implantation into TiN as-deposited by classical chemical vapor deposition onto cemented carbide substrates. After implantation the ions occupy an implanted zone (IZ) extending to a depth of about 80 nm. The transmission: electron microscopy study shows that implantation can lead to the formation of subgrains ih the IZ within the original grain structure without changing the grain size. The energy carried by the ions affects the material to far greater depths and a dislocation network is formed below the IZ, termed the implantation affected zone (IAZ). The dislocation density in the IAZ as determined here by. x-ray diffraction depends on the total energy carried by the:implanted ions. There is a threshold level before a compressive residual stress is developed after which the:stress is proportional to the energy reaching values as high as 3-4 GPa. A mechanism is proposed for the development of the IAZ where an oscillating stress field is developed at the boundary between the IZ and the IAZ and allows' the local emission of dislocation fluxes in mezobands into the IAZ.