The invention relates to a retractable animal leash assembly including a housing suitable for being held in one hand, an unwindable leash arranged partially coiled within the housing, a brake which is operable by the holding hand for momentarily blocking the portion of the leash located outside the housing at a desired length and a brake lock mechanism for holding the brake in the blocking position. The brake lock mechanism is activated with operating levers arranged in two positions on the housing reachable by the holding hand. Thus the housing can be held in either the left or the right hand without degradation of function and the prolonged switch may be easily and quickly operated by the holding hand or its fingers.