Aims: The aim of the study is to present patients, to who uncemented conic, polyethylene acetabular components of total hip endoprosthesis (EP) Endler model, were implanted. The study tries to establish whether the cause of aseptic loosening of polyethylene acetabular components is the particle disease itself, as a reaction on polyethylene, or the causes may be found in other factors as well. Materials and methods: In the period from 1985 to 1991, 100 patients (59 females and 41 males) were operated and 110 EP were implanted. The patients were followed from 10 to 16 years (median time – 12.47 years). In these study 72 patients with 80-implanted EP were evaluated (radiological, clinical and subjective evaluation). Results: In 42 (52.50%) implanted Endler acetabular components subjective, radiological and clinical findings were very good or excellent. In 38 (47.40%) implanted acetabular components reacetabuloplasty was performed due to aseptic loosening; in 22 of those components follow-up was 10 years and other 16 had follow-up of 11 to 16 years after the primary implantation. Conclusion: The results confirmed that aseptic loosening developed in one group of the patients (38 EP), but did not develop in the other group (42 EP) after long period. The comparison of postoperative biomechanic conditions which has not shown any statistically significant differences, led to conclusion that beside the main role of polyethylene and mechanic factors, immunological cell reaction and genetics can have an especially significant role. Necessities for new immunological studies in the application of total hip arthroplasty were stressed out by our results.