UNLABELLED: The purpose of the study was to evaluate the long-term results of uncemented total hip arthroplasty (THA) in young patients (below 50 years of age) with dysplastic coxarthrosis. In the last 20 years, 862 primary uncemented THA, were implanted in our Institution. This surgery was performed in 459 patients. From this group 220 hips in 177 patients (167 women and 10 men), who had dysplastic coxarthrosis, were included in our study. The left hip was operated in 66 and the right one in 68 patients. Bilateral surgery was performed in 43 cases. The means age at the time of hip surgery was 38.3 years (range from 18 to 49 years). The mean follow-up was 9.3 years (range from 2 years to 18.6 years). In 167 (75.8%) patients the operative treatment of DDH was performed during the early childhood (Colonna-Zahradnicek procedures, Dega, Pemberton and Salter pelvic osteotomies). Only 39 (17.7%) patients were treated in the childhood conservatively by means of overhead extension, Frejka pillow or Pavlik harness. All patients were evaluated clinically and radiological. For clinical evaluation the classification system proposed by Merle d'Aubigne and Postel with Chamley modification was used. For radiological evaluation of the steam implantation the classification system proposed by De Lee and Chamley was used and for the cup implantation the system by Gruen and Moreland. The femoral head displacement prior to THA surgery was classified according to Crowe at all. classification. Based on above mentioned criteria in 26 hips (11.8%) the final result was graded as very good, in 61 cases (27.7%) as good, in 94 hips (42.7%) as satisfactory and in the remaining 39 cases (17.8%) the final result was poor. We observed a very strong correlation between clinical and radiological results. According to Crowe and all. classification, in class I we noted 19 (61.3%) very good, 11 (35.5%) good, 1 (3.2%) satisfactory results. In class II in 5 cases (6.6%) the results was very good, 25 (32.9%) good and in 39 (51.3%) satisfactory results. In class III only in 2 cases the final result was graded as very good, and good in 23 hips (25.8%). In class IV there was no very good result, and we observed 19 (21.4%) poor results. In analyzed group in 37 (16.8%) patients the revision hip surgery was necessary because of aseptic prosthesis loosening. CONCLUSIONS: The treatment of dysplastic coxarthrosis by means of THA is difficult. The high level of experience is necessary to perform this type of surgery. This type of THA should be performed only in selected orthopaedic centers. Starting the surgery one has to think about complications.