The inhibition action of natural honey on the corrosion of copper in a 0.5 M sodium chloride solution has been evaluated by weight loss measurements and cathodic polarization technique. A good inhibition efficiency is observed which increases with an increase in inhibitor concentration. After some time, the inhibition efficiency decreased due to the growth of fungi in the medium. The Tafel slope is changed markedly in the presence of natural honey. The adsorption of natural honey on the copper/chloride interface is found to follow the Langmuir isotherm. (C) 1998 Elsevier Science Ltd. All rights reserved.