The term Frozen Shoulder (FS) is a medical colloquialism rather than a diagnosis. It is usually used as a clinical description with pathogenetic inferences, as suggested by the alternative designations of periarthritis, pericapsulitis, adhesive capsulitis and obliterative bursitis. Our understanding of the basic pathology and natural history of FS is limited, and this is reflected in the wide assortment of treatments which have been advocated. In this review the present state of knowledge of this disorder will be presented in a critical fashion.