Thromboelastometry ROTEM (Pentapharm, Munich, Germany) is a viscoelastic method of whole blood clotting assessment with applications in perioperative hemostasis and hematology. The different tests available for the investigation of distinct coagulation aspects are performed with combinations of liquid reagents. The use of liquid reagents for the ROTEM measurement requires several pipetting steps, which complicates their application in clinical routine even though pipetting is performed semiautomatically. New single portion reagents (SPR) containing in one vial all lyophilized reagents necessary for each test have been recently developed. SPR require only addition of blood into the single-use reagent vial in a unique pipetting step in order to mix reagents with the blood sample. Our study compared SPR and standard liquid reagents (Pentapharm) in 21 blood samples from normal subjects and 46 samples from patients in three study centers. Following ROTEM tests were performed: EXTEM (extrinsically activated TEM), INTEM (intrinsically activated TEM), FIBTEM (fibrin-based TEM), APTEM (aprotinin-controlled TEM) and HEPTEM (heparin-insensitive TEM). In the second part of the study, the stability of SPR at 37 degrees C was also assessed on 23 blood samples in one center. Very good correlation was found between SPR and liquid reagents for all clotting parameters (correlation coefficient between 0.85-0.99). The SPR reagents showed excellent stability against thermic stress and the measurements were easier to perform than with the conventional liquid reagents system.