We report the outcome of total hip arthroplasty (THA) in a cohort of patients with complete long-term radiographic and clinical followup information from our database of more than 48,000 primary hip replacements. The purpose of the study was to evaluate the influence of various demographic factors and patient comorbidity (Charnley classification) on the long-term outcome of THA. The cohort was comprised of 25,990 total hip replacements (THRs) in 10,243 (46.6%) men and 11,754 (53.4%) women with a median age of 66 years (range, 20-96 years) at the time of arthroplasty. Our study confirmed that THA has an impressive efficiency and reliability in alleviating pain and improving function for almost all of the patients. Furthermore, the results are enduring with more than 90% of patients being satisfied with the outcome at 15 years. Clinical outcome measures reach their maximum at 2 to 5 years after arthroplasty and thereafter they decline gradually. Furthermore, patient age, gender, body mass index, and main diagnosis all have an influence on specific functional parameters. The Charnley classification has the most profound effect on the overall functional status of patients.