Device for synchronizing the tilt of the back and the seat of a chair, of the type comprising a back frame, a seat frame and a support constrained to, or coincident with, the base of the chair, as well as at least one first crank hinged to the support and a front portion of the seat frame, and at least one second crank hinged to the support and a rear portion of the seat frame, so that the afore said at least one first and one second crank constitute a four-bar linkage with the seat frame. Advantageously, the device provides that the back frame is integral with the afore said at least one first crank.
