SUMMARY BACKGROUND Pretest probability assessment is necessary to identify patients in whom pulmonary embolism (PE) can be safely ruled out by a negative D-dimer without further investigations. OBJECTIVE Review and compare the performance of available clinical prediction rules (CPRs) for PE probability assessment. PATIENTS/METHODS We identified studies that evaluated a CPR in patients with suspected PE from Embase, Medline and the Cochrane database. We determined the 95% confidence intervals (CIs) of prevalence of PE in the various clinical probability categories of each CPR. Statistical heterogeneity was tested. RESULTS We identified 9 CPR and included 29 studies representing 31215 patients. Pooled prevalence of PE for three-level scores (low, intermediate or high clinical probability) was: low, 6% (95% CI, 4-8), intermediate, 23% (95% CI, 18-28) and high, 49% (95% CI, 43-56) for the Wells score; low, 13% (95% CI, 8-19), intermediate, 35% (95% CI, 31-38) and high, 71% (95% CI, 50-89) for the Geneva score; low, 9% (95% CI, 8-11), intermediate, 26% (95% CI, 24-28) and high, 76% (95% CI, 69-82) for the revised Geneva score. Pooled prevalence for two-level scores (PE likely or PE unlikely) was 8% (95% CI,6-11) and 34% (95% CI,29-40) for the Wells score, and 6% (95% CI, 3-9) and 23% (95% CI, 11-36) for the Charlotte rule. CONCLUSION Available CPR for assessing clinical probability of PE show similar accuracy. Existing scores are, however, not equivalent and the choice among various prediction rules and classification schemes (three- versus two-level) must be guided by local prevalence of PE, type of patients considered (outpatients or inpatients) and type of D-dimer assay applied.