Areas of fragmentation found in trabecular and cortical bone of iliac crest biopsy specimens have been described as bone quality defects and were thought to be the major factor responsible for femoral neck fractures. These appearances have also been regarded as cutting artefacts and to resolve this difference of opinion consecutive sections cut at right angles to each other in biopsy specimens from 15 patients with femoral neck fractures were compared. Sections were assessed by four independent observers; agreement by at least three was required before an area was accepted as a bone quality defect. In all, 270 were identified. Of the 161 found in sections cut parallel to the cortices, there were only 20 (12%) in coincident areas in consecutive sections. This study shows conclusively that areas of fragmentation previously described as bone quality defects are not artefacts which may be created or excluded depending on the plane of section.