A comprehensive study of haemostasis has been performed in a homogeneous group of 25 adult patients with conservatively treated chronic uraemia. We have found prolonged bleeding time, impaired platelet adhesiveness and aggregation, and decreased platelet factor 3 activity, increased values of fibrinogen, of factor VIII activity and related antigen, and of combined levels of factors II, VII and X. Non-significantly abnormal concentrations of factor XIII and of plasminogen and significantly lower values of plasminogen activators and higher values of urokinase inhibitors and anti-plasmin have also been found. Fibrinogen degradation products were detected in the urine of some patients.