Abstract: A variable angle radiation collimator particularly for use in gamma-photon medical diagnostic systems in a gamma-photon camera system for radiological examination of human subjects. The collimator provides collimation of gamma-photon radiation along a single beam direction which may be varied along two axes to adjust exposure angle or to provide a scanning capability. The collimator is a stack of substantially identical radiation-opaque plates, each of which are apertured with a similar array of openings. The combined effect of the stacked aperture plates is to transmit radiation in a predetermined orientation. The collimated angle of the radiation thus generated is controlled by the coincidence of the array of openings. The stack is retained by a mechanism which permits adjustment of the collimation angle, and the plates are fabricated to provide ease of shear motion during such adjustment.