This paper presents a comparative study of the atmospheric corrosion of bronze samples exposed for 12 months, at two sites: an urban atmosphere with intense traffic, in the city of Lisbon, and a rural marine atmosphere, Cabo da Roca, with a high degree of humidity, strong winds and high levels of chlorides all the year round. Exposures were started in the summer. Levels of SO2, NO2 and chlorides, in both atmospheres, were measured during the period of exposure. Climatic data for both sites was also collected and analysed. Weight losses and weight gains of samples with 4, 6, 8 and 12 months of exposure were measured and the average corrosion rates calculated. Chemical composition and morphology of the patinas formed during the exposure period, at both sites, were compared as well as the morphology of the corroded surfaces. Significant differences, related to the level of pollutants and meteorological variables, were found.