This study is an attempt to derive a relationship between steel reinforcement corrosion and the coinciding loss of flexural strength. The corrosion of the steel was isolated in the flexural region in order to eliminate contributions from stirrup corrosion and loss of bond within the development length. It was determined that the flexural capacity of reinforced concrete beams decreased as the rate of corrosion increased. In addition to the study of flexural capacity, the prediction of the flexural behaviour of corroded beams was studied through the stiffness effects of reinforcement corrosion. The stiffness study indicated a sharp drop in stiffness at relatively low degrees of corrosion, followed by a slower decline at increasing levels of corrosion. Mass loss, crack width and chloride ion content were examined as indicators of degree of corrosion. These relationships are an essential step in developing an effective model for the performance of corroded reinforced concrete beams in the future.