Frost's bulk-staining technique clearly separates artifactual cracking in bone from that caused by mechanical loading in vivo. One-centimeter sections of human rib were either bulk stained before preparation of a thin section (experimental) or stained after grinding to a thickness of 150 microns (control). Microdamage produced before preparation can be separated from that caused by the preparation itself. Moreover, the technique does not cause additional artifactual cracking through dehydration. This technique provides a valid way to test hypotheses about the role that microdamage creation or its repair plays in skeletal pathology.