Abstract: A venetian blind having prismatic reflective slatted panels permits the passage of indirect rays of sunlight into a space to be illuminated while reflecting direct rays of sunlight away from the space to be illuminated. The prismatic reflective slats are supported for rotation in unison to follow elevational movements of the sun. Each of the prismatic panels is made from a light transmissive material having a front face directed at the sun and an opposing rear face upon which reflective prisms are formed for internally reflecting rays of sunlight that strike the front face of each slatted panel at approximately a 30.degree. angle from a line normal to the front face thereof. The orientation of the reflecting prisms in this manner maximizes overall visibility between adjacent slatted panels. A diffusion panel is secured to the rear face of each prismatic reflective slat for diffusing indirect rays of sunlight transmitted through the prismatic reflective slats.