Objectives: This study aims to assess early changes in physical activity and function after total hip arthroplasty (THA) using both subjectiveand objective methods, and to identify predictors of outcomes of THA.Patients and methods: Between October 2014 and October 2015, a total of 50 patients (14 males, 36 females; mean age 57.1±13.0 years;range, 31 to 75 years) with end-stage primary hip osteoarthritis who were scheduled for THA and 50 age- and sex-matched controls(10 males, 40 females; mean age 52.9±9.3 years; range, 36 to 75 years) were included in the study. Pain was evaluated using the NumericRating Scale (NRS), physical function using the Lequesne Index, physical capacity using the Six-Minute Walking Test (6MWT), and physicalactivity using both International Physical Activity Impact Questionnaire Short Form (IPAQ-SF) and step count monitor. Data at baselineand six weeks and six months were recorded.Results: Pain severity was significantly lower after THA at six weeks and six months (NRS scores: 2.83 and 0.82, respectively; p<0.001),compared to baseline. Physical function, capacity, and activity significantly improved after THA at six weeks and six months with a meanLequesne Index score of 2.62 and 1.02, respectively. The mean 6MWT distance was 272.62 at six weeks and 326.16 at six months. The meanIPAQ and 6MWT results were similar between the patient and control groups at six weeks and six months. Age, presence of comorbidities,and baseline Lequesne Index score were found to be effective on functional outcomes of THA. Age and baseline 6MWT scores were correlatedwith physical capacity after THA.Conclusion: Our study showed a significant early improvement in pain severity and physical activity and function at six weeks and sixmonths after THA, compared to baseline values. Baseline values and age were the positive predictors of improved postoperative functionand physical capacity.