SummaryCommonly used coagulation technics are not useful for detection of hypercoagulable states. Increase of factor VIII coagulation activity and particularly of factor VHI-related antigen is evident in hypercoagulable states but not pathognomonic.Cold promoted activation of factor VII, wellknown during oestrogen therapy, is found in IS % of individuals without hormonal therapy. It is not yet known whether that activation can be related with thrombotic states.Increase of plasma antiheparin activity could be related to platelet factor 4 release. Such increase is sometimes observed in thrombotic accidents but is not found in all cases.