The effect of two different regimens of hormone replacement therapy on coagulation and fibrinolysis was measured in 30 women taking Tibolone (Livial) and 30 taking oestradiol valerate, sequentially combined with cyproterone acetate (Climen). Blood samples were taken before the beginning of the medication, then six and twelve months afterwards. The Livial group showed a rise of fibrinolytic activity as measured by the alpha 2-antiplasmin-plasmin complexes. Tissue plasminogen activator antigen and plasminogen activator inhibitor-1 decreased simultaneously. No effect was seen in the coagulation variables. In the Climen group no significant alterations were noticed, either in the coagulation or in the fibrinolysis variables. In the direct comparison of both substances only factor VII appeared to be significantly higher in the Climen group after six months and one year of treatment.