Therapeutic apheresis is a widely used treatment alternative for several diseases. In 29 patients with different diseases, we have monitored the PT, aPTT, thrombin time (TT), fibrinogen, D-dimer, factor VIII, IX, X, XI, XII, VWF, Protein C, S, Active Protein C Resistance (APCR) and Antithrombin-III during TPE. Patients were divided into four groups based on the replacement fluids used: 3% VARIHES or ISOHES + 4% albumin (1: 1) (group 1), fresh frozen plasma (FFP) (group 2), 3% VARIHES or ISOHES (group 3) and 4% albumin (group 4). In our study, the fibrinogen level decreased to 83% of the base line level after the end of 48 h therapy. The APTT, PT, and TT increased during TPE. However no statistical difference was observed between the groups. We found a significant change in factor levels with time, only the difference in factors IX and XI between the groups was significant. In addition, factor levels measured at 48 h were close to the levels measured before aphereses. In our study, time the related change in AT-3 values was significant. Time-related changes of the Protein S and APCR were not statistical significant significant but on the other hand, we found a significant difference in AT-III and Protein C values between groups. The side effects of HES on coagulation factors and tests were comparable to those of other replacement fluids. Its low cost makes it favourable. (C) 2003 Elsevier Science Ltd. All rights reserved.