Increasing demand for high quality castings has increased the importance of computed tomography (CT) in the casting industry. With computed tomography it is possible to cover the whole sample-volume. Apparent differences in density can be detected and size and positions of these inhomogeneities can be determined in three dimensions. CT is a valuable tool because various casting defects can be detected and quantified. This paper highlights the possibilities and limitations of computed tomography for quality control and assessment of castings from materials to finished products. Considerable improvements can be achieved using volume rendering with novel multi-dimensional transfer functions for visualising the volume data. In particular the quantification of casting defects were addressed and compared to standard metallographic procedures and common CT analysis-tools.