From June 1985 to September 1986, eight patients affected by sacrococcygeal chordoma were examined by means of conventional radiography and tomography first, and then by high-resolution CT. All patients underwent surgery and an histologic examination of the surgical specimen was carried out. CT always allowed to detect the sacro-coccygeal neoplasm, which looked like a solid non-homogeneous mass; in 50% of cases coarse calcifications were found. CT made it possible to evaluate the growing side of the tumor, its relation with the adjacent anatomical structures-especially the longitudinal extension and the involvement of the sacral hiatus; these findings proved to be very useful in order to choose the most appropriate surgical technique. CT findings also suggested the nature of the tumor but rarely allowed a definitive diagnosis. CT is, at any rate, mandatory in order to evaluate the real extent of the tumor and to plan surgery.