Periprosthetic joint infection (PJI) following total hip arthroplasty (THA) is a devastating problem for surgeons, but worse for the patients involved. If diagnosed early, prompt intervention and treatment can vastly improve outcomes. Increased risk of PJI relates to decreased ability to fend off disease, along with modifiable and non-modifiable risk factors. PJI occurs due to either surgical site contamination, local spread or spread from a distant infection elsewhere in the body. Gram-positive organisms remain the most common causative microbes. Patients with PJI can present with a range of symptoms, from florid sepsis to decreased performance in a well-functioning joint. Here, the array of diagnostic tests available are used, and these are the focus of this article. The Second International Consensus Meeting on Musculoskeletal Infection 2018 advocated a scoring system for pre- and intraoperative non-microbiological tests. It highlights the importance of using multiple tests in tandem when faced with a failing arthroplasty or prosthesis, but with no organism cultured. Treatment options range from traditional two-stage revision surgery, through to single-stage surgery and antibiotic suppression. Treatment plans must be patient-specific, but all are significant undertakings. Therefore, the role of prevention must continue to be at the forefront of any arthroplasty surgeon's mind.