Plasma von Willebrand factor (vWF) was evaluated as a potential biomarker of acute arterial damage in rats after a vasotoxic dose of the dopaminergic vasodilator, fenoldopam (FP). Male Sprague-Dawley rats were given FP or isotonic saline by subcutaneous injection, and plasma vWF was measured at 2, 6, and 24 hours after challenge. Mean plasma vWF values increased in FP-treated rats compared to controls at 2 hours (167 vs 122%; p < 0.05) and 6 hours postdose (172 vs 130%; p < 0.01) but were comparable to control values after 24 hours. Mesenteric arterial lesions were observed microscopically in all FP-treated rats 24 hours postdose but were not present in rats at 1, 2, 4, 6, or 8 hours after FP challenge. Further, plasma vWF concentrations increased in saline-treated rats after only the minimal perturbation of repeated venipuncture. These results indicate an early, minimal, and transient release of vWF that precedes the onset of morphologically evident vascular damage. The minimal increases in plasma vWF concentrations were of limited predictive value, may be more reflective of an acute-phase reactant response, and were not considered a reliable biomarker of acute FP-induced arterial damage in the rat.