Introduction The term ‘subarachnoid haemorrhage’ (SAH) stands for bleeding into the subarachnoid space, regardless of its source. It may be of primary character when the source of bleeding is situated within the subarachnoid space. Subarachnoid haemorrhage is often described as spontaneous bleeding, mainly in order to differentiate it from post-traumatic bleeding. Objective The aim of the study was to evaluate the concentration of ICAM-1 and VCAM-1 in the blood of patients in the early phase following subarachnoid haemorrhage in terms of searching for markers useful in subarachnoid bleeding diagnostics and monitoring a patient’s clinical state. Material and Methods The study comprised 85 patients (47 women, 38 men), aged 29–81 (average 53±12 years), suffering from subarachnoid haemorrhage. The control group comprised 45 healthy people selected according to gender and age corresponding with the experimental group. Results The study revealed that the concentration of ICAM-1 and VCAM-1 was significantly higher in patients suffering from subarachnoid haemorrhage. Additionally, the concentration of fibrinogen decreased, aPTT was shorter and the concentration of D-dimers increased. The studied parameters did not differ with respect to the age or gender of the patients. It was stated that according to the Hunt and Hess scale, the concentration of ICAM-1 was considerably higher in the group of patients in the most severe neurological state, compared to other patients. It was also observed that the concentration of fibrinogen was significantly higher, aPTT was shorter, and the concentration of D-dimers increased in the afore-mentioned group. Conclusions Evaluation of the concentration of adhesion molecules, as well as values of global tests concerning the coagulation system, may serve as a useful diagnostic tool for SAH.