Background: Nucleosomes are cell death products that are elevated in serum of patients with diseases that are associated with massive cell destruction. We investigated the kinetics of circulating nucleosomes after cerebral stroke and their correlation with the clinical status. Methods: In total, we analyzed nucleosomes by ELISA in sera of 63 patients with early stroke daily during the first week after onset. For correlation with the clinical pathology, patients were grouped into those with medium to slight functional impairment (Barthel Index BI >= 50) and those with severe functional impairment (BI < 50). Results: Patients with BI >= 50 showed a continuous increase in nucleosomes until day 5 (median: 523 arbitrary units, AU) followed by a slow decline. In contrast, patients with BI < 50 showed a steeper initial increase reaching a maximum already on day 3 (869 AU). Both, days after stroke (p < 0.001) and BI (p < 0.001), had a significant influence on nucleosome concentrations, respectively. Consistently, patients with BI < 50 had a significantly larger area under the curve (AUC/day) of nucleosome values during the first week after stroke (800 AU) than patients with BI >= 50 (497 AU; p = 0.031). Concerning the infarction volume, nucleosomes showed significant correlations for the concentrations on day 3 (r = 0.43; p = 0.001) and for the area under the curve (r = 0.34; p = 0.016). Conclusion: Even if nucleosomes are nonspecific cell death markers, their release into serum after cerebral stroke correlates with the gross functional status as well as with the infarction volume and can be considered as biochemical correlative to the severity of stroke. Copyright (c) 2006 S. Karger AG, Basel.