A utility knife for receipt of a blade and including a handle and a blade carrier pivotally connected to the handle. A threaded fastener fastens a blade retainer to the blade carrier, and the threaded fastener is preferably configured for engagement by the user's hand to move the blade carrier between the retracted position and the extended position. A locking member automatically locks the blade carrier in an extended position upon the blade carrier being moved to the extended position. An actuator moves the locking member against the force of a spring from the locking position to the unlocking position, the actuator extending from the first side of the handle to the second side of the handle. A storage compartment is configured for receipt of plurality of blades, and a closure member allows selective access to such blades.