High resolution spectral measurements of reflectance and transmittance of leaves ofVicia faba L. exposed to sulphur dioxide were taken using an integrating sphere. Changes in detailed spectral-curve shape, found by analysing spectral first derivatives, were caused by exposure to sulphur dioxide concentrations between 200nl1−1and 800 nl1−1for ten day periods. Analysis of spectral derivatives may provide a quantitative method for specific remote identification of plant stress induced by sulphur dioxide in the field. The spectral effects of sulphur dioxide on leaves are examined in relation to leaf structural properties and pigments.