Post-irradiation sarcomas of head and neck appear seldom, and among them leiomyosarcoma (LMS) is exceptionally rare. 11 cases of this tumour, associated with previous irradiation and situated in this anatomical area have been described so far. The aim of this study was to describe 56 year-old patient with LMS and to compare this case with the others described in the literature. What brought our attention were scanty clinical symptoms coexisted with extensive radiological changes. Radiotherapy can give rise to the development of LMS in different moments of time after the treatment of primary tumor has been finished. In this aspect patients who undergone radiotherapy in the early stage of live and who are more susceptible to this kind of treatment should be followed up more closely and carefully.