Investigations have been made of the various factors considered to influence the sensitivity of the microradiographic method for the examination of alloys. Both target element and applied voltage influenced the results. Radiographs are shown to demonstrate the effect; an explanation is given in terms of the x‐ray emission curves and the absorption differential curves for the phases of the radiographed alloy. Target‐specimen distance was an important factor for uncollimated rays, particularly for distances of less than 6 in. with minute inhomogeneities or with low values for the absorption differential. The size of inhomogeneity, lower limit of absorption differential, and upper limit of magnification were also studied. For investigation of the distribution of elements in inhomogeneities, it was concluded that, contrary to previous reports, both target element and applied voltage must be carefully chosen after a study of the absorption differential curves. The optimum voltage range is usually 2.5 to 3.5 times the excitation potential.