SummaryIn this study we assessed the reliability of a rapid bed-side whole blood D-dimer assay prospectively in patients with clinically suspected venous thromboembolism, referred to the Academic Medical Centre, Amsterdam. In consecutive outpatients with clinically suspected deep vein thrombosis or pulmonary embolism we measured the sensitivity, specificity and negative predictive value of the assay compared to the outcome of standard diagnostic tests and 3-month follow-up. A total of 234 patients were included; the prevalence of venous thromboembolism was 29%. A sensitivity, specificity and negative predictive value of 100% (95% Cl: 95% -100%), 58% (95% Cl: 50% - 65%) and 100% (95% Cl: 96% -100%), respectively, were obtained. The exclusion rate was 41% of all referred patients. Conclusion: The SimpliRED whole blood D-dimer assay appears to be a simple and reliable method for the exclusion of venous thromboembolism in symptomatic outpatients.