AbstractSodium dodecyl sulphate and mercaptoethanol are commonly used for extraction and solubilization of proteins, but these substances interfere with previously reported methods for the quantitation of small amounts of protein. In order to overcome this difficulty, a method has been developed for assaying small quantities of protein by (i) spotting the protein solution on a polyvinylidene difluoride membrane, (ii) staining the membrane bound protein with Coomassie Blue, (iii) destaining, and (iv) determining the optical density of the stained membrane by laser‐based scanning. The determination of proteins in conifer foliage by this method is describe