A venetian blind comprises a plurality of pairs 1 of horizontal slats 3, 5 which are connected together at the ends by means of a rope or tape 15. The Figure shows the venetian blind in partially closed position. The slats can rotate around the longitudinal axis both clockwise and anti-clockwise, so that the top or bottom respectively is rotated to the side facing the window. The venetian blind has cords to which the slats are attached with their longitudinal edges. By pulling at the cords the slats can be rotated clockwise or anti-clockwise.