Microsaccades (MSs) are the largest fixational eye movements, but their role in visual perception is not fully understood. Some recent studies suggest that in natural vision, there may be a direct link between MS activity and perceptual improvement. Other evidence demonstrates that MS dynamics are influenced by cognitive factors including spatial attention, working memory, and ocular and manual motor preparation, suggesting that their occurrence relates to the active sampling of the environment. We used a visual illusion to examine the effect of perceptual state on MS patterns. We analyzed the eye movements of three monkeys performing the Generalized Flash Suppression (GFS) task (Wilke et al, 2006). In GFS the presentation of a salient target is followed by the abrupt onset of a surround pattern, at which point the target either remains subjectively visible (visible trials) or seems disappeared completely (invisible trials). Eye movements were monitored using scleral search coils, and were processed offline to detect MSs within the first second, in which the target was either visible or invisible. We found that when fixating subjects experienced GFS, MSs after the presentation of the surrounding patterns occurred in about 5% and 35% of the “invisible” and “visible” trials respectiv