A cable operated bone anchor compressor and a method for thoracoscopically compressing bone anchors are disclosed. In procedures in which bone anchors, such as bone screws, are fixed to bone tissue and such bone tissue is to be readjusted or realigned, the device of the present invention is thoracoscopically inserted. The device includes a cable to be placed in contact with one bone anchor, and an elongated member with a mating head to be placed against another bone anchor. When the cable is retracted, the bone anchors are compressed or pulled toward each other to realign, in a desired fashion, the bone tissue to which they are attached.