We announce the discovery of a new satellite of the Milky Way in the constellation of Bootes at a distance of ∼60 kpc. It was found in a systematic search for stellar overdensities in the north Galactic cap using Sloan Digital Sky Survey Data Release 5. The color-magnitude diagram shows a well-defined turnoff, red giant branch, and extended horizontal branch. Its absolute magnitude is Mv∼ -5.8 mag, which makes it one of the faintest galaxies known. The half-light radius is ∼220 pc. The isodensity contours are elongated and have an irregular shape, suggesting that Boo may be a disrupted dwarf spheroidal galaxy.