The first part of this study retrospectively compared the discriminatory power of spiral CT versus clinical findings in 112 consecutive patients referred with chest pain or dyspnoea. Spiral CT exhibited a sensitivity 91.9%; specificity 98.7%; PPV 97.1%; NPV 96.1%; accuracy 96.4%. No other test or clinical parameter had acceptable accuracy. The SimpliRED test is a latex method of estimating the level of D-dimer. The second part of this study determined that, in a similar consecutive series of patients referred for lung scintigrams, although SimpliRED tests had a NPV 95.5%, 59/126 (46.8%) consecutive were positive. However on the basis of clinical effectiveness and cost, imaging for suspected pulmonary embolism should be based on a combination of D-dimer estimation and spiral CT.