Authors present long-term functional outcomes of acquired peri-prosthetic ossifications complicating primary and revision hip arthroplasty. Aim of the paper was realized based on clinical material of 1995-2005, 142 patients was included to the study, 64 (45.1%) men and 78 (54.9%) women aged between 44-75 years (average 62 years) with periprosthetic ossifications after primary and revision hip arthroplasty done through the posterolateral surgical approach. Observation period was between 1-6 years (average 3 years). Study group of 142 patients made up 67.3% of all periprosthetic ossification diagnosed in during the analyzed period. Pharmacological and radiological pre and postoperative prophylaxis of periprosthetic ossifications was not done in this group. Clinical material was divided into three age groups and according to type of implants creating the study group. Diagnosed ossifications were classified according to Brooker classes. Evaluation of obtained outcomes was done basing on Harris criterions and compared to outcomes obtained in control group, which was separated from existeding Clinic data base. Control group made up 142 patients without periprosthetic ossifications, 64 (45.1%) men and 78 (54.9%) women aged between 37-78 years (average 66 years), observation period between 1-3 years (average 2 years).