Little is known about the spatial vision of mice or of the role the visual cortex plays in mouse visual perception. In order to provide baseline information upon which to evaluate the spatial vision of experimentally and genetically altered mice, we used the visual water task to assess the contrast sensitivity and grating acuity of normal C57BL/6 mice. We then ablated striate cortex (V1) bilaterally and re-measured the same visual functions. Intact mice displayed an inverse "U"-shaped contrast sensitivity curve with a maximum sensitivity near 0.2 cycles/degree (c/d). Grating acuity, measured either by discriminating a sine-wave grating from an equiluminant gray, or vertical from horizontal sine wave gratings, was near 0.55 c/d. Grating acuity and contrast sensitivity were reduced significantly following aspiration of V1. The mouse visual system exhibits fundamental mammalian characteristics, including the feature that striate cortex is involved in processing visual information with the highest sensitivity and spatial frequency.