Laboratory measurements of the spectral reflectance of leaves from a variety of species were made over the 400-2500 nm range using a spectroradiomctcr. The relation between spectral reflectance and leaf water content was investigated and the effect of differences in leaf structure were found to be important. The first derivative of the reflectance spectrum, at wavelengths corresponding to the slopes on the edges of the water absorption bands, was found to be highly correlated with leaf water content and insensitive to differences in leaf structure.