To evaluate the activation of the extrinsic pathway of coagulation in disseminated intravascular coagulation (DIC), plasma factor VII coagulant activity (FVIIc) and antigen levels (FVIIag) were measured in 81 blood samples obtained from the 56 patients with DIC together with various hemostatic parameters. Plasma FVIIc (77 +/- 40%, range: 11-200%) and FVIIag (76 +/- 43%, range: 16-175%) were significantly lower in DIC subjects than in age-matched controls (FVIIc: 128 +/- 28%, FVII: 128 +/- 31%, p less than 0.01) and correlated significantly with both the antithrombin III and plasminogen activities (p less than 0.001). These results indicated that a decrease in factor VII levels is due to the consumption. However, there were several exceptions which showed elevated factor VII levels. This seems to be due to enhanced liver synthesis of factor VII compensating for the consumption. The level of tPA-PAI-I complex, a marker of pathologic endothelial stimulation, was negatively correlated with FVIIag (r = 0.45, p less than 0.05). Thus, the more the endothelium is pathologically stimulated, the more the extrinsic pathway is activated in DIC. The FVIIc/FVIIag ratio, an index of activation of factor VII zymogen, correlated with FDP and fibrin monomer levels (p less than 0.01). There were no correlations between the thrombin-antithrombin III complex. D-dimer, and alpha 2 antiplasmin-plasmin complex levels and factor VII levels. Considering the underlying diseases. the FVIIc and FVIIag levels were markedly lower in liver cirrhosis, but not significantly different in other diseases.(ABSTRACT TRUNCATED AT 250 WORDS)