We measured three selected components of the fibrinolytic system in amniotic fluid of 36 parturient women, i.e. the antigen of tissue plasminogen activator (tPA) and antigens of plasminogen activator inhibitor of type 1 (PAI-1) and type 2 (PAI-2). The ELISA method was used. During labour, the level of each of the studied antigens increases; tPA antigen increases over five times (0.91 ± 0.32 ng/ml before labour and 5.92 ± 1.83 ng/ml after childbirth), which is statistically significant, while at the same time the increase in PAI-1 and PAI-2 antigen levels is small and thus statistically insignificant. As the result of unequal changes, the prelabour dominance of PAIs over tPA decreases intra partum (tPA/PAIs ratio 1:1,038 before labour and 1:164 after childbirth), and yet the multiple dominance of PAIs over tPA remains.