C-1-inactivator (C-1-INA) does not only exert its important inhibitory functions in the complement system but also in the first step in the activation of the coagulation, fibrinolytic and kallikrein system. We therefore determined in nine patients with hereditary angioneurotic oedema (HANE) with obvious quantitative or functional defects of C-1-INA, and one further patient with Quincke-type oedema of different origin, the coagulation factors of the initial phase such as Hageman factor, plasma thromboplastin antecedent (PTA) and high molecular weight kininogen (HMWK). These factors were further correlated with the concentration as well as functional activity of C-1-INA. Nine of ten patients showed a significant, sometimes even excessive, increase in the levels of factor XII (mean +/- SD = 146% +/- 63), HMWK (mean +/- SD = 126% +/- 56) and PTA (mean +/- SD = 289% +/- 294), and a decrease of C1-esterase inhibitor (C-1-inactivator), which was measured with a immunologic method (mean +/- SD = 9.6 mg/dl +/- 6.6) for its concentration as well as being measured for its activity (mean +/- SD = 30.4% +/- 24.9).