Abstract: A sight proof, drainable blade louver assembly for use in the wall of a building or other enclosure to permit outside air to enter the building, the louver having a plurality of spaced apart blades arranged between spaced apart vertical jambs of a frame in a vertical stack. Each blade has an upwardly inclined first portion and a second portion which is inclined downwardly from the first portion, thus giving each blade the configuration of an inverted V. The leading or free edge of the first portion has a vertical flange which extends upwardly partly to the blade thereabove, and a lip which extends obliquely from the free edge of the vertical flange partly back to the first portion. The free edge of the second flange has a vertical flange which extends downwardly therefrom partly to the blade therebelow.