With a view to their possible exploitation, the composition of Pinus pinaster leaves was studied, with the following results: ash content, 3.08% w/w; proteins, 7.45%; Klason lignin, 24.36%; polysaccharides, 34.93%; waxes, 11.68% (determined as the combined hexane- and benzene-extractable fractions); and components extracted by polar organic solvents, water and NaOH solution, 46.81%. This final fraction, the most abundant and the most interesting as regards exploitation of this material, was principally comprised of polyhydroxy polyphenols. These can form polymeric gels with formaldehyde, and are thus potential substitutes for phenol in the manufacture of adhesives.