Total hip replacement is a common and effective procedure with a high success rate. I have studied the etiology of total hip replacement pain from my regular clinical practice, as well as evaluating the pain. In many cases, history, physical examination, and proper research can determine the cause of total hip replacement pain and therefore allow for appropriate treatment. There are two main causes of pain after total hip replacement: I. Intrinsic Causes (1) Aseptic loosening; (2) Infection; (3) Instability; (4) Periprosthetic fracture; (5) Bursitis; and (6) Thigh pain-pain in the tip of the femoral stem prosthesis. Second, Extrinsic Causes If the pain after arthroplasty is similar to the preoperative period, this looks like the hip etiology is not causing the pain symptoms. As an example, symptoms due to lumbar and sacroiliac etiologies are similar to those of hip osteoarthritis, occurring as thigh, buttock, and occasionally groin area pain. Spinal stenosis is one of the most commonly used differential diagnoses. Hip dysmobility in this subset of cases should be painless, but occasional comorbid spinal stenosis is not recognized until the patient’s mobility is gradually increased after total hip replacement. However, such pain has a different character from that of the preoperative period. Other degenerative, inflammatory spinal, or sacroiliac joint problems can be identified on the basis of a detailed history and examination, and can also be confirmed by radiologic, CT, or MRI studies. However, in some cases, it is difficult to rule out spinal causes of pain based on examination and research, and diagnostic local anesthetic hip injections may be helpful. Pain may also be associated with Paget’s disease, which can coexist with osteoarthritis of the hip. The disease can produce postoperative pain but should be sensitive to medical treatment. The femoral, sciatic, and lateral femoral cutaneous nerves can be directly injured intraoperatively or indirectly by lengthening of the limb as a result of total hip replacement, producing burning skin pain. Metastatic disease from pelvic, lumbar, or femoral fracture tumors can produce symptoms that can be mistaken for total hip dysfunction and pain. Such metastatic disease may not be radiologically evident and may be confusing to recognize due to internal fixation. This condition has a classic history of rest pain or nocturnal pain. In closing, I wish each and every one of you health, happiness and joy!