Slit radiography is a highly efficient means of suppressing scatter. However, when employed with a pulsating x ray source, a grid line type of artifact results if the movement of the slit is not properly coupled to the periodicity of the source. Taking the exposure of the film to be the convolution of the slit transmittance and the radiation intensity, the conditions for a uniform exposure have been derived for the realistic configuration of a multiple slit array and a slit transmittance that includes the focal spot and slit geometry. Expressions for the amplitude and spatial frequency of the artifact when the conditions are not met are derived. Methods of suppressing the artifact when its vanishing conditions are not met are also discussed. © 1981, American Institute of Physics for the National Institute of Standards and Technology. All rights reserved.