The effects of orientation and spatial frequency of grating stimuli upon suppression were examined with a binocular rivalry paradigm in a group of ten strabismic patients and in a control normal group. Duration, frequency, and period of rivalry were examined as functions of differences in orientation and spatial frequency of dichoptic achromatic sinusoidal gratings. Records were made of responses by the sighting and by the nonsighting eye as well as responses during periods of combined binocular vision. Strabismic subjects reported normal binocular rivalry when presented with gratings of dissimilar orientation. Suppression of the deviating eye in strabismic subjects occurred with stimuli of similar orientation and was unaffected by spatial-frequency differences between dichoptic stimuli. Suppression was most intense under conditions that normally stimulate stereopsis and sensory fusion.