Prosthetic joint infection (PJI) is one of the worst complications of joint arthroplasty with an incidence of around 1% following primary arthroplasty, 3% following aseptic revision, and 20% following septic revision. It can occur following direct inoculation, haematogenous or contiguous spread. The majority of PJIs are secondary to bacterial infection although fungal PJI may be seen in multiply operated or immune compromised patients. Risk factors for PJI include patient, pathology and procedure-related factors which, where possible, should be optimized prior to surgery. The diagnosis of PJI remains a challenge and is based on patient history, clinical examination, laboratory tests, and imaging studies. No diagnostic assessment is 100% accurate with various diagnostic criteria used clinically. Investigation and treatment of PJI should be guided by a multi-disciplinary team. Surgical treatment remains the gold standard with the aim of eradicating infection. During surgery the causative organism is sought through a rigorous standardized tissue sampling technique. Surgical approaches including debridement, antibiotics and implant retention (DAIR), single-stage revision, two-stage revision, excision arthroplasty, arthrodesis and amputation. The approach used is tailored to the individual patient with the optimum surgical strategy being one that successfully eradicates the infection, but at the same time minimizes morbidity to the patient.