BACKGROUND–To determine the relationship between chiropractic manipulative therapy (CMT) and internal carotid artery dissection (ICAD), a MEDLINE literature search was performed for the years 1966 through 2000 using the termsinternal carotid dissection.Literature that included information concerning causation of ICAD, as well as all case studies and series, was selected for review.REVIEW SUMMARY–In reviewing the cases of internal carotid dissection potentially related to CMT, there were many confounding factors, such as connective tissue aberrations, underlying arteriopathy, or coexistent infection, that obscured any obvious cause-and-effect relationship. To date there are only 13 reported cases of ICAD temporally related to CMT. Most ICADs seem to occur spontaneously and progress from local symptoms of headache and neck pain to cortical ischemic signs. Approximately one third of the reported cases were manipulated by practitioners other than chiropractic physicians, and because of the differential risk related to major differences in training and practice between practitioners who manipulate the spine, it would be inappropriate to compare adverse outcomes between practitioner groups.CONCLUSIONS–The medical literature does not support a clear causal relationship between CMT and ICAD. Reported cases are exceedingly scarce, and none support clear cause and effect.