Quality control was implemented in 52 dental intra-oral X ray units in use in the public and private sector in Hellas. The protocol consisted of visual inspection of the X ray unit, complete registration of the unit's characteristics, measurement of the unit's radiological parameters, inspection of the radiation protection facilities for patient and personnel and examination of film processing conditions. The results are characterised by the large number of old X ray units, the great variability in entrance surface doses and linearity of output and the absence of strict patient and operator radiation protection measures. Analogue exposure timers have very poor accuracy compared to digital ones. Imaging techniques and film processing do not always comply with standards among dentists. In view of the above, the implementation of a Quality Control programme, including refernce doses, which could, for example, be selected according to the results of this paper, is strongly recommended in Dental Radiology in Hellas.