Abstract: The invention relates to a chair comprising at least a chassis; and a seat, as well as means suitable for converting chair movements into control signals for controlling a cursor (pointer) on a display screen. In order to prevent RSI complaints, the invention aims at providing an improved chair, which is characterized in that the seat comprises a convex part, which part can be movably accommodated in a corresponding part of the chassis having a complementary concave shape, and in that the means for controlling the cursor are at least in part disposed at the location of the mating area between said convex and concave parts.