A dishwashing machine having a load-bearing structure and a washtub , there being articulated to the load-bearing structure a front door of the tub , the machine moreover having a system for extraction of damp air from the tub , which comprises a fan and a discharge duct having a hollow body with a width dimension of and a height dimension, wherein the fan is a radial fan having a fan housing housed in which is a centrifugal impeller , the fan housing having an intake mouth and a delivery , wherein the discharge duct has an inlet portion and an outlet portion , the intake mouth of the fan housing being in fluid communication with an outlet opening of the tub , the inlet portion of the discharge duct being in fluid communication with the delivery of the fan housing , and the outlet portion of the discharge duct being at the front of the machine , wherein at least the outlet portion and the intermediate portion of the discharge duct extend above an upper wall of the tub , with the outlet portion above an upper edge of the door , wherein the outlet opening is formed in one of the upper wall and a stationary side wall of the tub , with the fan housing , which is mounted on said wall (3a; 3c) with the respective intake mouth at the outlet opening and set substantially coaxial thereto, in such a way that damp air is drawn in from the outlet opening substantially in the direction of the axis (A) of the impeller and forced in a radial direction into the discharge duct , and then expelled from the outlet portion at the front of the machine above the upper edge of the door , the dishwashing machine being characterized in that the discharge duct has a portion intermediate with respect to the inlet and outlet portions , the height (H) of which decreases in a substantially progressive way towards the outlet portion and the width (W) of which increases in a substantially progressive way towards the outlet portion and in that the outlet portion of the discharge duct comprises an outlet divided into a plurality of suboutlets . wherein the fan is a radial fan having a fan housing housed in which is a centrifugal impeller , the fan housing having an intake mouth and a delivery , wherein the discharge duct has an inlet portion and an outlet portion , the intake mouth of the fan housing being in fluid communication with an outlet opening of the tub , the inlet portion of the discharge duct being in fluid communication with the delivery of the fan housing , and the outlet portion of the discharge duct being at the front of the machine , wherein at least the outlet portion and the intermediate portion of the discharge duct extend above an upper wall of the tub , with the outlet portion above an upper edge of the door , wherein the outlet opening is formed in one of the upper wall and a stationary side wall of the tub , with the fan housing , which is mounted on said wall (3a; 3c) with the respective intake mouth at the outlet opening and set substantially coaxial thereto, in such a way that damp air is drawn in from the outlet opening substantially in the direction of the axis (A) of the impeller and forced in a radial direction into the discharge duct , and then expelled from the outlet portion at the front of the machine above the upper edge of the door , the dishwashing machine being characterized in that the discharge duct has a portion intermediate with respect to the inlet and outlet portions , the height (H) of which decreases in a substantially progressive way towards the outlet portion and the width (W) of which increases in a substantially progressive way towards the outlet portion and in that the outlet portion of the discharge duct comprises an outlet divided into a plurality of suboutlets . <EOS>