Described is a carriage (7) for sliding doors and windows (2) comprising a fixed frame (3), at least one sash (4) that is slidable horizontally relative to the fixed frame (3) by means of a carriage unit (1), and a handle (9) mounted on the sash (4) for controlling the carriage (7); the latter is provided with a supporting frame (11), mobile on wheels, and with a connecting member (13) interposed between the supporting frame (11) and a bottom sash (4) rail (8); the connecting member (13) is movably constrained to the supporting frame (11) to enable the sash (4) to be lifted and lowered relative to the supporting frame (11) under the action of the handle (9); a helical spring (44) is interposed between the supporting frame (11) and the connecting member (13) to lessen the effort required of the user to lift the sash (4).