Abstract: Process for preventing activation of enzyme systems such as coagulation and activation of complement system or bradykinin system in extracorporeal blood circulation in haemodialysis and similar procedures, by means of sequential anticoagulation, which comprises adding in the first 15 to 30 minutes of haemodialysis or of similar procedure, sodium citrate or nafamostat mesylate, into a dialysis line as anticoagulant, then stopping the addition of citrate or nafomostat mesylate, and adding heparin in the conventional total dose, until the end of dialysis.By using this process, a universal routine haemodialysis or a similar procedure, is made possible without further adaptations according to the kind of patient.