Herein described is a two-stroke internal combustion engine (100), comprising: a cylinder (135) having a pre-set central axis (B); a piston (145) slidably coupled to the cylinder (135) and suitable to divide the interior volume thereof into two distinct chambers, including a combustion chamber (150) and a pumping chamber (155); an intake duct (160) communicating with the pumping chamber (155); an exhaust duct (170) communicating with the combustion chamber (150); and at least one scavenging duct (180) suitable to place the pumping chamber (155) in communication with the combustion chamber (150); wherein said scavenging duct (180) comprises a terminal portion (190) leading to the combustion chamber (150) which extends with configuration diverging from an inlet section (200) up to an outlet section (205) obtained on a lateral surface of the cylinder (135).