The localisations of bone cysts known under the title of "intraosseous ganglion, synovial cyst of bone and solitary unicameral cyst" are summarised from the literature. Two of the authors' patients are added to the few cases of talar cysts recorded up to the present. In addition, a patient with a calcaneal cyst is described. The cysts can be traumatic or non-traumatic in origin. The various theories concerning their etiology are discussed. The clinical findings, differential diagnosis and therapy of subchondral bone cysts particularly in the region of the foot are considered.