It is well known that visual transients can abolish the execution of an eye movement about 90 ms later, a phenomenon known as saccadic inhibition (SI). But it is not known if the same inhibitory process might influence covert orienting in the absence of saccades, and consequently alter visual perception. We measured orientation discrimination performance in 14 participants during a covert orienting task (modified Posner paradigm) in which an uninformative exogenous visual cue preceded the onset of an oriented probe stimulus by 120 to 306 ms. In half of the trials the onset of the probe was accompanied by a brief irrelevant flash, a visual transient that would normally induce SI in an overt task. We report a SI-like time-specific covert inhibition effect in which the irrelevant flash impaired orientation discrimination accuracy only when the probe followed the cue between 165 to 265 ms. The interference was more pronounced when the cue was incongruent with the probe location. We suggest that covert orienting may be susceptible to similar inhibitory mechanisms that generate SI in overt orienting, although the precise time course and mechanisms of this novel effect require further characterisation.