OBJECTIVE: To examine whether there is a difference in the frequency of infections in patients with primary hip endoprosthesis compared to patients with a revising hip endoprosthesis. Furthermore, to investigate whether there is a difference in the cause and the treatment of the infection between the two mentioned groups of examinees, and to determine the frequency of infections with regard to the age, gender and body side. STUDY DESIGN: Cross–sectional study PARTICIPANTS AND METHODS: The study included 98 subjects with a postoperative infection (primary and revising) of both genders and of all age groups treated at the Department of Orthopedics KBC Osijek in the period from 2011 to 2016. The data from the letters of release, the history of the illness and the outpatient journals have been taken and processed from the medical records of the Department of Orthopedics KBC Osijek. RESULTS: There is no significant difference in the frequency of infections in the first and the second group of examinees. There is a significant difference in the causes of infection in the first and second group of examinees. The significantly most common cause of infection in subjects with primary endoprosthesis (the first group) is methylcilin resistant coagulase negative staphylococci. In the second group of subjects, the more frequent cause of infection is Pseudomonas aeruginosa. In the treatment of the infection of primary endoprosthesis patients, the antibiotic rifampicin was more frequently used, whereas with a significant part of patients with revising endoprosthesis it is not known whether antibiotics were used in the treatment. CONCLUSION: The most common causes are coagulase negative staphylococci and methicillin resistant Staphylococcus aureus. With regard to the primary and revising ednoprothesis, there was a difference in the type of the cause of infection. The most commonly used antibiotics are vancomycin and clindamycin.