A door handle assembly includes a lock casing having an inner cam and an outer cam and a latch bolt, an indoor handle device attached to an inner portion of the lock casing with an actuating device and having a handgrip for being depressed to actuate an actuating bolt and the inner cam to operate the latch bolt, and an outdoor handle device attached to an outer portion of the lock casing with another actuating device and having another handgrip for being pulled to actuate another actuating bolt and the outer cam to operate the latch bolt, the outdoor handle device and indoor handle device are replaceable with each other when the actuating devices are disposed up-side-down.