With the resurgence of clinical trials in spinal cord injury (SCI), there is intense interest in whether the American Spinal Injury Association (ASIA) standards are sensitive enough to discriminate neurological recovery. We conducted a systematic review to examine the psychometric properties of the ASIA Standards in assessing motor and sensory function of individuals with acute traumatic SCI. Papers, which examined the psychometric properties of the ASIA Standards, were obtained from Medline, CINAHL, and EMBASE databases (1982-2008). Of 39 publications primarily identified, 18 fulfilled the inclusion and exclusion criteria. An additional 51 publications were captured in a secondary search using the bibliographies from original articles and published reviews. The 2000 version of the ASIA Standards appear to be more reliable than the previous versions, although two prospective studies indicate that the ASIA Standards do not reliably assess children less than 4 years with SCI. Responsiveness studies indicate that (a) a detailed neurological examination using the ASIA Standards at 72 h should be obtained for comparison with subsequent neurological assessments following SCI; (b) the use of ASIA upper- and lower-extremity motor subscores instead of a single ASIA motor score is recommended; (c) further investigation of the minimal clinically important difference of the ASIA Standards is required; and (d) the functionally meaningful ASIA score threshold to document the benefit of a novel therapeutic intervention varies according to the level and severity of SCI. Although the ASIA Standards cannot be evaluated in terms of criterion validity, several studies suggested their divergent and convergent construct validity. Therefore, the ASIA Standards represent an appropriate instrument to discriminate and evaluate patients with SCI in a longitudinal manner. Nonetheless, further investigation of the ASIA Standards is recommended due to a paucity of studies focused on some key elements of the measurement responsiveness, including minimal clinically important difference.