A surface cleaning apparatus comprises an air flow passage 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 passage. 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. Various design improvements are provided.