The ability of laser irradiation to destroy tissue is well known. Less
well known is the fact that the same radiation, at much lower intensi
ties, can non-destructively alter cellular function. This latter pheno
menon, which occurs in the absence of significant heating, is now a ba
sis for the conservative treatment of a variety of musculoskeletal, ne
urological, and soft tissue conditions in many parts of the world. Thi
s review first examines the 25-year history and scientific basis of ''
laser therapy.'' Clinical applications are discussed and the reasons f
or its relative lack of acceptance in the US are examined. The article
concludes with an overview of current research and the impact it will
have on laser therapy's role in US clinical practice.