This project investigates the detection and evaluation of imperfections in internal structures of castings and welded joints by x-ray radiography. Optimum radiography conditions that lead to clear and high contrast image on the radiograph were studied. Equations derived earlier for finding the size and depth of defects in castings were used in this project to test their applicability to a wide range of geometrical parameters used in radiography. The importance of non-destructive testing NDT in industry is discussed. X-ray radiography being one of the NDT techniques, has some privilege over other techniques. For example, welded joints sometimes contain internal flaw or blowholes that may escape detection by other NDT techniques but can not escape detection by x-rays. Two kinds of samples are prepared for radiography. The first sample is aluminum casting through which two different sizes of steel spheres are included. This sample was radiographed from two opposite sides and the x-ray films were analyzed.The second sample is steel plates which are welded by arc welding and then radiographed by x-rays. Imperfections in this sample such as incomplete root penetration, undercut and porosity were detected by x-ray radiography. Different conditions influencing the preparation and radiography of the above samples were studied. The prepared welded sample was radiographed three times for different high voltages (120,140,160) kV respectively with an exposure time of (80) second. The best quality image where the defects can be detected clearly if its size is (5%) of the radiographed object using (120) kV and (140) kV. Moreover the results show that the optimum film gradient was found at (140)kV and the contrast is better than obtained with (120)kV while darkening image was found at (160)kV. In field of the aluminum casting, the two equations were derived earlier proved their capabilities as a right method for identification each of size and depth of such defects in castings and welded joints