The objective of this systematic review was to assess whether pre-operative brain natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT pro-BNP) are independent predictors of adverse outcomes after cardiac surgery. MEDLINE, Embase and the Cochrane Controlled Trials Register databases were searched. Eligible studies included observational or randomized control trials measuring natriuretic peptide concentrations before induction of anaesthesia for cardiac surgery. Two investigators independently extracted the data and assessed the validity of the included studies. The predictive ability of pre-operative BNP or NT pro-BNP on mortality, post-operative atrial fibrillation (AF) and intra-aortic balloon pump (IABP) requirement was meta-analysed. The association between BNP or NT pro-BNP and other outcomes was systematically summarized. A total of 4933 patients from 22 studies were considered in the systematic review. Ten studies with one or more outcomes of interest were included in the meta-analyses. The strength of association between pre-operative natriuretic peptide levels and adverse outcomes after surgery was variable, as was the size and quality of the included studies. The summary areas under the receiver operating characteristic curve for mortality, post-operative AF and post-operative IABP requirement were 0.61 (95% confidence interval [CI] 0.51-0.70), 0.61 (95% CI 0.58-0.64) and 0.81 (95% CI 0.73-0.89), respectively. With the limited data available, the associations between pre-operative natriuretic peptide levels and adverse outcomes after cardiac surgery were moderate. Future studies should assess whether pre-operative natriuretic peptides can provide additional independent predictive information to well-validated prognostic scores of cardiac surgery.