Low molecular weight phenolics were analyzed by HPLC in oak heartwood of Quercus robur L., Quercus petraea Liebl., Quercus pyrenaica Wild., and Quercus faginea Lam. Data were processed with the STATGRAPHICS program. Gallic, ellagic, vanillic, syringic, and ferulic acids, vanillin, syringaldehyde, coniferaldehyde, sinapaldehyde, aesculetin, and scopoletin were found. Ellagic and gallic acid derivatives were also recognized according to their hydrolysis products and their UV spectra. Q. robur and Q. petraea differ from the others by the relative concentration of these compounds.