Two new 2-naphthoic acid derivatives have been isolated from the aqueous extract of the heartwood of Ulmus thomasii Sarg. They have been shown to be 6-hydroxy-5,7-dimethoxy-2-naphthoicacid (I) and 6-hydroxy-3-hydroxymethyl-5,7-dimethoxy-2-naphthoic acid lactone (IV). The NMR spectra of several related naphthols and naphthoic acids and their derivatives have been examined. Acetylation of naphthol derivatives