Evidence for rapid neural computation in visual cortex are now available: Event related potentials in human visual system have revealed a frontal negativity specific to no-go trials involving complex shape categorization that develops roughly after 150 ms stimulus onset. Furthermore, in Vl, in the inferotemporal cortex, and in the superior temporal sulcus, cells can discriminate different complex visual stimuli within 5 to 10 ms. Given the anatomical and physiological constraints imposed by our knowledge of the visual system, such data have major implications for theories of visual computation. The suggestion that firing rate is rarely in excess of one spike in a 5-10 ms period in cortex emphasizes this situation. Cortical maps, which reflect a precise topographic neuronal organization where neighboring sites of maximum relative activity on the cortical plane correspond to nearby points in parameter space, might offer a neural substrate for rapid computation.