The issue of hypercoagulability in acute asthmatic attacks is controversial. This may be due to lack of an appropriate test to monitor overall coagulation. Current hematologic tests do not account for the cellular fraction of blood that has procoagulant activity. Our study uses a clotting assay called the modified recalcification time test that is performed with whole blood to ensure the contribution of all chemical and cellular mediators in the coagulation process, particularly tissue factor. Venous blood samples were obtained from 12 adult patients with acute exacerbation of asthma or chronic obstructive pulmonary disease and compared with samples from 12 age-matched healthy control subjects. By use of the modified recalcification time, the presence of a relative hypercoagulable state was demonstrated in patients with acute bronchospasm. Furthermore, there is an identifiable difference in modified recalcification time value between the patients with acute attacks who required hospital admission versus those discharged from the emergency department.