The authors point out that when TEP are planned more attention is paid to the type of prosthesis, its composition and technical parameters and less attention to the quality of osseous tissue which is the subject of the present work. The authors examined at the First Orthopaedic Clinic Medical Faculty Comenius University Bratislava by means of a densitometer LUNAR DPX L the neck of the femur in patients before implantation of a TEP. They examined 96 coxae in patients with an average age of 57 years. Primary coxarthrosis accounted for 48%, bionecrosis of the head for 21%, deforming coxarthrosis (condition following LCC) 12%, rheumatoid arthritis 9%, conditions after fractures of the neck of the femur 9%. In the first group the bone density - BMD per g/cm2 in the neck of the femur (K) was 0.996 (109%), of Ward's triangle (W) 0.902 (118%), of the trochanter (T) 0.748 (106%). Values in the other groups: Group 2: K = 0,823 (93 %), W = 0,702 (91 %), T = 0,587 (76 %). Group 3: K = 0,987 (107%), W = 0,814 (99%), T = 0,684 (89 %). Group 4: K = 0,740 (83 %), W = 0,586 (74 %), T = 0,479 (64 %). Group 5: K = 0,604 (66 %), W = 0,533 (68 %), T = 0,513(63%). The results indicate that in idiopathic coxarthrosis the density is normal or elevated, in deforming coxarthrosis the coxa is difficult to examine by means of our software. In rheumatoid arthritis bionecrosis and mainly after fractures is density reduced. Reduced bone density is associated with the firmness of the fixation of TEP. Key words: DEXA, DPX, bone density, total endoprosthesis.