We report upon a case of 62 years old Saudi male with non-Hodgkin lymphoma who developed lichen planus (LP) on the inner aspect of the upper lip six months after finishing radiotherapy. The diagnosis of LP was confirmed by histopathology. Literature review reveals few countable similar reports of “post radiotherapyoral LP (OLP)”. However, the isolated location of lichen planus on the upper lip per se in this case merits reporting being exceptional and reported before as isolated lichen planus of the lips (ILPL). We assume, after screening literature, that this is the first report of post radiotherapy ILPL in Arabian Gulf countries, though it may be underestimated and underreported. The etiological relation between radiotherapy and LP is discussed