Abstract: A dental x-ray diagnostic installation comprises x-ray apparatus containing x-ray generator and x-ray tube having a hollow anode in the form of applicator for insertion in the interior of a patient's mouth. In order to facilitate the construction and handling of the apparatus in particular the insertion of the applicator in the mouth, the x-ray apparatus is designed as a unit capable of being positioned on a table or on a wall and contains a stationary member or part, which supports a horizontal axle which pivotably connects a housing containing the x-ray tube and the applicator on the stationary member for pivotable movement therewith. In addition, the installation includes a bite-on part which has a bite piece and a sleeve, which telescopically receives the applicator and enables the patient to locate the applicator in the desired position within the mouth.