To investigate the occurrence and extent of activation of coagulation after endoscopic variceal sclerotherapy (EVS), we performed serial measurements of conventional coagulation tests [prothrombin time (PT), partial thromboplastin time (PTT), platelets, and fibrinogen], and of plasma fibrinopeptide A (FPA) in 39 cirrhotic patients undergoing 55 sessions of elective EVS. Thrombin (20 U/ml) and sodium morrhuate 5% were used in sequence as sclerosants on 34 occasions. In the remaining 21 sessions, sodium morrhuate 5% alone was used. Conventional coagulation tests did not change significantly after EVS, regardless of the type of treatment. Basal plasma FPA levels were abnormally high in about 50% of patients. After EVS, plasma FPA increased sharply in 37/39 patients (95%), returning to baseline values in most of them within 24 h. We conclude that transient systemic activation of blood coagulation occurs after EVS. Such activation can be detected only by sensitive methods such as FPA assay, and has no effect on conventional coagulation tests. This, and the absence of any clinical EVS-related coagulation disorder in our patients, suggests that activation of coagulation should not be a major concern for patients undergoing EVS.