Periprosthetic joint infection (PJI) is a serious and potentially devastating complication of total joint arthroplasty. Accurate diagnosis of PJI is of utmost importance, but differentiating septic from aseptic failed total joint arthroplasty is extremely challenging, and improper management can lead to significant morbidity. The gold standard for PJI diagnosis is based on standardized laboratory and clinical criteria but relies on preoperative and intraoperative findings, which can be unreliable. Given these limitations, research has focused on new methods for diagnosing PJI. Synovial fluid inflammatory cytokines have been found to accurately diagnose PJI. In this article, we review the synovial fluid cytokines that are being used as aids in PJI diagnosis.