Endothelins (ETs) are potent vasoconstrictor and may play a role in the pathophysiology of several cardiovascular diseases. Endothelin-mediated vasoconstriction may enhance ischemic neuronal damage. The study aimed to find out whether the plasma ET-1 levels may serve as marker of early ischemic stroke. Plasma ET-1 levels were tested in 20 patients with acute ischemic stroke, mean age 63.7 +/- 5.03 years, 12 men and 8 women, within 24 hours of stroke onset as compared to 10 sex- and age-matched control subjects; only the patients with normal CT-scan at admission were included in the study. Plasma ET-1 was measured by ELISA. The results were statistically analyzed by Student test and a p < 0.05 (95% CI) was considered statistically significant. ET-1 levels in patients with hemiplegia and normal CT-scan at admission were significantly higher as compared to control group (0.0910 +/- 0.0256 pg/mL vs. 0.0490 +/- 0.0185 pg/mL, p < 0.0001) (95% CI). Ischemic stroke is associated with acute and marked increased levels of ET-1 in plasma. This may reflect enhanced production by damaged endothelial cells within the infarcted lesion. ET-1 may be used as additional marker of cerebral ischemia in selected cases to distinguish between the onset of an ischemic stroke and other non-vascular diseases presenting similar symptoms.