Objective: Although all intracompartmental pressure (ICP) measurement, magnetic resonance imaging, and near-infrared spectroscopy seem to be useful in confirming the diagnosis of chronic exertional compartment syndrome (CECS), no standard diagnostic procedure is currently universally accepted. We reviewed systematically the relevant published evidence on diagnostic criteria commonly in use for CECS to address 3 main questions: (1) Is there a standard diagnostic method available? (2) What ICP threshold criteria should be used for diagnosing CECS? (3) What are the criteria and options for surgical management? Finally, we made statements on the strength of each diagnostic criterion of ICP based on a rigorous standardized process., Data Sources: We searched for studies that investigated ICP measurements in diagnosing CECS in the leg of human subjects, using PubMed, Score, PEDRO, Cochrane, Scopus, SportDiscus, Web of Knowledge, and Google Scholar. Initial searches were performed using the phrase, "chronic exertional compartment syndrome." The phrase "compartment syndrome" was then combined, using Boolean connectors ("OR" and "AND") with the words "diagnosis," "parameters," "levels," "localisation," or "measurement." Data extracted from each study included study design, number of subjects, number of controls, ICP instrument used, compartments measured, limb position during measurements, catheter position, exercise protocol, timing of measurements, mean resting compartment pressures, mean maximal compartment pressures, mean postexercise compartment pressures, diagnostic criteria used, and whether a reference diagnostic standard was used. The quality of studies was assessed based on the approach used by the American Academy of Orthopaedic Surgeons in judging the quality of diagnostic studies, and recommendations were made regarding each ICP diagnostic criteria in the literature by taking into account the quality and quantity of the available studies proposing each criterion., Main Results: In the review, 32 studies were included. The studies varied in the ICP measurement techniques used; the most commonly measured compartment was the anterior muscle compartment, and the exercise protocol varied between running, walking, and ankle plantarflexion and dorsiflexion exercises. Preexercise, mean values ranged from 7.4 to 50.8 mm Hg for CECS patients, and 5.7 to 12 mm Hg in controls; measurements during exercise showed mean pressure readings ranging from 42 to 150 mm Hg in patients and 28 to 141 mm Hg in controls. No overlap between subjects and controls in mean ICP measurements was found at the 1-minute postexercise timing interval only showing values ranging from 34 to 55.4 mm Hg and 9 to 19 mm Hg in CECS patients and controls, respectively. The quality of the studies was generally not high, and we found the evidence for commonly used ICP criteria in diagnosing CECS to be weak., Conclusions: Studies in which an independent, blinded comparison is made with a valid reference standard among consecutive patients are yet to be undertaken. There should also be an agreed ICP test protocol for diagnosing CECS because the variability here contributes to the large differences in ICP measurements and hence diagnostic thresholds between studies. Current ICP pressure criteria for CECS diagnosis are therefore unreliable, and emphasis should remain on good history. However, clinicians may consider measurements taken at 1 minute after exercise because mean levels at this timing interval only did not overlap between subjects and controls in the studies we analyzed. Levels above the highest reported value for controls here (27.5 mm Hg) along with a good history, should be regarded as highly suggestive of CECS. It is evident that to achieve an objective recommendation for ICP threshold there is a need to set up a multi-center study group to reach an agreed testing protocol and modify the preliminary recommendations we have made.