The inhibition efficiencies of Anemone coronaria Extract (ACE) on the corrosion behaviour carbon steel in molar hydrochloric acid have been evaluated by weight loss method, potentiodynamic porarization curve and electrochemical impedance spectroscopy (EIS) measurements. The effects of inhibitor concentrations are studied at various concentration of inhibitor at 298 K. The obtained results reveal that Extract of this plant is an effective inhibitor. Potentiodynamic polarization measurements studies showed that Anemone coronaria Extract act essentially as cathodic-type inhibitor for steel in 1.0 M HCl. The inhibition efficiency increased with increasing concentration to attain a value of 90.07% at 2 g/L. E(%) values obtained from various methods used are reasonably good agreement. Electrochemical impedance data demonstrate that the addition of the Anemone coronaria Extract in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Adsorption of these inhibitors on the steel surface obeys to the Langmuir adsorption isotherm.