Rotational thromboelastometry is recommended to guide haemostatic therapy in trauma-related coagulopathy. In the case of unsuccessful venepuncture, intraosseous access allows immediate administration of drugs and volume replacement. Feasibility of rotational thromboelastometry from intraosseous blood has not yet been investigated in humans. We performed rotational thromboelastometry and standard coagulation assays from intraosseous and intravenous blood samples in 19 volunteers and 4 patients undergoing general anaesthesia. Intraosseous access was performed either at the tibial bone or the proximal humerus. We observed visible clotting in the majority of the intraosseous samples. Only 13% of the probes allowed realization of rotational thromboelastometry. ROTEM parameters are reported as follows: shorter median clotting time (CT) in EXTEM, INTEM, and APTEM (53 vs. 68 s; 140 vs. 154 s; 54 vs. 62.5 s) and smaller median maximal clot firmness (MCF) in EXTEM and APTEM (56 vs. 63 mm; 55 vs. 62 mm) in intraosseous samples. We found no relevant differences in median MCF values in FIBTEM and INTEM (12 vs. 13 mm; 60 vs. 59 mm). Given the difficulties we faced during IO blood sampling in a study setting, we advise against ROTEM measurements out of IO blood for guidance of procoagulant therapy in emergency situations.