An improved guide device (10) for the opening and the support of furniture doors suitable for guiding and supporting the movement thereof both during opening and closing phases, comprising a container body (11) of substantially rectangular shape attached on the inner face of a lateral shoulder (12) of a frame of an item of furniture (14) provided with a door (16) fall-front openable via at least one hinge (18) attached to the frame of the furniture (14) and operatively connected to the container body (11) by means of a cable (20) attached to said door (16) via a fastening element (22) constrained to an inner face of the same door (16), said device which likewise comprises a body-slide (48) sliding inside said container body (11) and integrating means roto-translating with respect to a cogged profile or rack (32) of the container body (11) for a movement of said body-slide (48) and an unwinding/winding of said cable (20) in contrast to or assisted by a return spring and/or by damping means.