Arthrocreisis operations of the subtalar joint by means of calcancal endoorthosis performed in the three year period 1982-84 arc reviewed. The different anatomoc1inica1 forms of valgus flat foot, a condition to be considered as a syndrome with various actiopathogenic and morphological aspects arc nosographically identified. The case series consists of 44 subtalar arthrocreisis operations either alone or in combination with other surgical techniques. Each case was subjected to clinical examination (subjective assessment, walking, podoscopy, examination of the relationship between the hind and fore foot, joint parameters and muscle function) and X-rays (latcromedial, dorsoplantar, postcroanterior projections under load and sagittal stratigraphy of the hind foot). The results, generally highly satisfactory are examined. In particular it is emphasised that the technique is simple, fast and extremely effective. In addition the extent of the correction is easily regulated and the operation does not interfere with the physiology and biomechanics of the pcriastragalar joints. In general postoperative recovery times were extremely short.