Testicular torsion (TT) is a urological emergency that affects one in 4000 males younger than 25 years. Delays in the management of TT may result in testicular ischaemia, testicular necrosis, orchidectomy and infertility. This review assesses the validity of near-infrared spectroscopy (NIRS) as a diagnostic tool in the assessment and diagnosis of TT.A systematic search of Cochrane Database of Systematic Reviews, EMBASE, Google Scholar, PubMed, Scopus and Web of Science databases was performed in January 2019 using specific search terms. Selected studies were ranked and evaluated using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and the Quality Assessment of Diagnostic Accuracy Studies-2 tool.A total of nine studies that included 253 subjects (88 animals and 165 humans) with a mean sample size of 28.1 (standard deviation 40.8) subjects were included. The mean difference in testicular tissue oxygen saturation between torsed and non-torsed testes (Δ%StO ) were 45%, 42% (±5%), 26% and 5-18% in four animal studies and 2.0%, 3.0%, 6.7%, 6.8% and 23.0% in five human studies. The tissue oxygen saturation difference between contralateral healthy testes (controls) ranged from 1% to 10% in the five studies that alluded to this.The current body of evidence does not support the use of NIRS in the work-up of TT. Well-designed clinical trials with large patient samples are required to determine whether NIRS may have some future role as a diagnostic modality in TT.