An exhaust muffler comprising first and second shell members connected to each other to form an inner region, an inlet formed on said first shell member for admitting exhaust gases from an internal combustion engine into said inner region, a number of discharge ports formed on a wall part of said second shell member which faces said inlet, a cover shell extending over the outside of said wall part of said second shell member for forming therewith an elongated cooling channel having an air inlet opening at one end and a diffusing outlet opening at the other end in the axial direction of said cooling channel, a discharge hood associated with each of said discharge ports for deflecting exhaust gases flowing out of said discharge ports from said inner region into said cooling channel in the direction of said diffusing outlet opening, said cover shell and said wall part together defining a Venturi tube in the longitudinal cross-section of said channel, said discharge hoods being arranged successively in the longitudinal direction of said cooling channel wherein said wall part deflects in the direction opposite from said cover shell by an angle (.alpha.) of about 2.degree. to 8.degree. after the last successive one of said discharge hoods in the direction of said diffusing outlet opening of said channel for maintaining gas flow in said cooling channel contiguous to said wall part.