Applying contemporary data fusion techniques, the multi-modal nondestructive testing (NDT) data sets can be combined to obtain more reliable results. The reliability can be quantified in terms of the probability of detection of sought material defects. A concise review of the published studies on NDT data fusion is provided here and the key concepts and anticipated challenges are discussed. The detailed steps involved in the NDT fusion process are explained with reference to a case study. The presented data set includes the results of three different NDT techniques on a test specimen with built-in defects. Several pixel-level fusion algorithms were applied and their performances are quantitatively compared.