A surface cleaning apparatus comprises an air flow path extending from a dirty air inlet to a clean air outlet and a suction motor. The surface cleaning apparatus may also comprise a cyclone chamber provided in the air flow path. The cyclone chamber may comprise a cyclone air inlet, a cyclone air outlet and a dirt outlet. The surface cleaning apparatus may comprise a dirt collection chamber having a dirt inlet, a dirt collection chamber first end, an opposed dirt collection chamber second end and a longitudinally extending sidewall. The sidewall may comprise a portion that has a longitudinal length and extends away from the dirt inlet towards the opposed dirt collection chamber second end. A transverse cross sectional area of the dirt collection chamber may varies at least once along the length of the portion of the sidewall.