Abstract The debate over the effects of the timing of surgical spinal decompression after traumatic spinal cord injury (tSCI) has remained unresolved for over a century. The aim of the current study was to perform a systematic review and quality-adjusted meta-analysis of studies evaluating the effects of the timing of spinal surgery after tSCI. Studies were searched for through the MEDLINE(®) database (1966 to August 2012) and a 15-item, tailored scoring system was used for assessing the included studies' susceptibility to bias. Random effects and quality effects meta-analyses were performed. Models were tested for robustness using one way and criterion-based sensitivity analysis and funnel plots. Results are presented as weighted mean differences (WMDs) and odds ratios (ORs) with 95% confidence intervals (CIs). A total of 18 studies were analyzed. Heterogeneity was evident among the studies included. Quality effects models showed that - when compared with "late" surgery - "early" spinal surgery was significantly associated with a higher total motor score improvement (WMD: 5.94 points, 95% CI:0.74,11.15) in seven studies, neurological improvement rate (OR: 2.23, 95% CI:1.35,3.67) in six studies, and shorter length of hospital stay (WMD: -9.98 days, 95% CI:-13.10,-6.85) in six studies. However, one way and criterion-based sensitivity analyses demonstrated a profound lack of robustness among pooled estimates. Funnel plots showed significant proof of publication bias. In conclusion, despite the fact that "early" spinal surgery was significantly associated with improved neurological and length of stay outcomes, the evidence supporting "early" spinal surgery after tSCI lacks robustness as a result of different sources of heterogeneity within and between original studies. Where the conduct of a surgical, randomized controlled trial seems to be an unfeasible undertaking in acute tSCI, methodological safeguards require the utmost attention in future cohort studies. (Prospero registration number: PROSPERO CRD42012003182. See also http://www.crd.york.ac.uk/NIHR_PROSPERO/ ).