Heparin and hirudin antidotal compositions and methods

A method of at least partially reversing the anticoagulation activity of a blood anticoagulant in a mammal comprising administering to said mammal a therapeutically effective amount of Factor VIII or fragments of Factor VIII which retain its activity or a substance which increases its concentration in blood, wherein the blood anticoagulant is selected from the group consisting of heparin, anticoagulantly active heparin fragments, low molecular weight heparins, fragmin, thrombin inhibitors, hirudin, synthetic hirudin variants, hirudin derivatives, hirudin fragments, desulphatohirudin variants, (2R, 4R)-4-methyl-1-[N.sup.2 -(3-(RS)-methyl-1,2,3,4-tetrahydro-8-quinolinyl-sulphonyl)-(S)-arginyl]-2- piperidine carboxylic acid, D-phenyl-alanyl-L-prolyl-L-arginine aldehyde sulphate, and N.alpha.-(2-naphthalene-sulphonyl-glycyl)-4-amido-phenylalaninepiperidine.