For diagnosis of pulmonary embolism (PE), ventilation/perfusion lung scintigraphy is routinely used; approximately one-third of the patients will have the diagnosis "intermediate probability of PE" (inconclusive). In this group only about 33% are found to have pulmonary emboli if examined with pulmonary angiography. To evaluate the diagnostic, therapeutic, and economic consequences of ultrasound of the legs as a complementary diagnostic investigation to "intermediate probability", 72 consecutive patients were investigated with bilateral ultrasound of the proximal deep veins of the legs and pulmonary angiography in a prospective study. Ten patients had PE, of whom 7 had deep venous thrombosis, and 62 had no PE, of whom 2 had deep venous thrombosis. The negative predictive value of ultrasound was 0.95. In view of the importance of adequate treatment and rational use of public health care expenditure, complementary diagnostics should be performed, and ultrasound is an adequate complementary investigation.