The corrosion inhibition effect of allium sativum(garlic) extract as a ‘green’ inhibitor on α-brass in 0.5M HNO3 was studied at ambient temperature. Weight loss and corrosion rate and potentiodynamic polarization measurement techniques were used for the experimental work. Potentiodynamic polarization measurement was performed using a potentiostat (Autolab PGSTAT 30 ECO CHIMIE) interfaced with a computer for data acquisition and analysis. The obtained results showed effective corrosioninhibition of the garlic extract on the test-specimens in the different concentrations of the test medium. There was increasing inhibition performance with increasing concentration of inhibitor. The best inhibition performance was achieved with the 100% (as extracted) garlic concentration. In 0.5M HNO3, 100% garlic gave the optimal performance with weight loss of-0.021g, polarization resistance value of 6.88E+03 Ω, corrosion rate, CR, of 3.44E – 02 mm/yr and current density (Icorr) value of 3.74E-06 A/cm2. Results of ba and bc indicate a mixed type inhibitor.