Background: Regarding the frequency of Total Hip Arthroplasty (THA) operation and controversies arisen considering the etiologic factors, treatment outcomes, and complications, the present study was performed over the patients referring to Imam Hossein and Pars Hospitals between 1994 and 1998. Materials and methods: It was a retrospective study of existing data type, where, patients undergone THA and followed up for at least two years were study. Initial data, etiologic factors, treatment outcomes, and complications were determined. Results: We studied 80 patients and 96 hips. There were 42 men and 38 women with a mean age at surgery of 48.5±13.1 years. The most frequent cause of THA was primary degenerative arthritis (36%), hip dysplasia (30%), and fracture of femoral neck (25%). Hip dysplasia and primary degenerative arthritis were the most common cause of THA in females and males, respectively. Complete and partial pain relief was reported in 88.7% and 11.3% of the patients. 5 patients have required accessory devices for walking. Patients with hip dysplasia were more susceptible to develop postoperative complications. The most frequent complications were prosthesis dislocation, difference in leg length, and neural complication. No case of postoperative infection, fracture, emboli, bladder and urinary tract injury or vascular complications was reported. Conclusion: With respect to differences found in etiology and complications with that appeared in references, epidemiological studies are strongly recommended.