Abstract: A self-propelled rotary lawn mower. The drive shaft of the engine is operably connected through a clutch mechanism to the cutting blade and to a belt drive connected the front wheels to drive the mower across the terrain. By disengaging the clutch through manual action of a cable, the driving connection to both the blade and the wheels is stopped, so that the blade will not rotate when the mower is stationary. The housing of the mower includes inner and outer housing sections with the space between the housing sections defining a chamber. The exhaust gases from the engine are directed into the chamber and are discharged from the chamber adjacent the grass discharge outlet in the housing. Directing the exhaust gases through the internal housing chamber substantially decreases the noise level of the mower. The four wheels of the mower are adapted to be raised and lowered in unison by single lever control to thereby vary the height of the blade above the ground.