Objective: To review the available literature pertaining to the therapeutic benefits of the audible release associated with spinal manipulative therapy. A critical appraisal of the scientific literature, empirical evidence and theories relating to this aspect of manipulation is presented. Data source: A broad based search of the English language literature was conducted utilising the databases Medline (1966-1998), Mantis (Health Index) (1880-1998) and Cumulative Index to Nursing and Allied Health (CINAHL) (1982-1998), using the key words crack/ing, cavitation, audible release, gapping, sound/s, noise/s, vibration, biomechanics, coupled with joint, articular, manipulation, spinal manipulation and spinal manipulative therapy. A manual search was also conducted of non-indexed journals and text books relating to manual therapy of the library of RMIT University, Bundoora, Victoria as well as a broad based Internet search. Results: There is a paucity of scientific research relating to this specific aspect of spinal manipulative therapy. Although there is ample empirical evidence to support some therapeutic benefit from the audible release, only one scientific study specifically relating to this topic was uncovered. Conclusion: Currently there is little scientific evidence to support any therapeutic benefit derived from the audible release and in fact, it appears the available evidence tends to refute many of the alleged beneficial effects. Given that many practitioners and patients alike place an importance on this aspect of manipulation further research is required in order to fully investigate this phenomenon.