Anticoagulant activity, total and nonenzymatic fibrinolytic activity, and tissue plasminogen activator activity increased, while platelet aggregation and activity of factor XIIIa in rat blood plasma decreased over 3 h after single intranasal administration of proline-containing peptide Pro-Gly-Pro. Hemostatic parameters in rats 24 h after single administration of this peptide did not differ from the control level observed in animals receiving 0.85% NaCl.