An unprecedented natural acetophenone, polygonophenone (1), and a new resorcinol, polygonocinol (2), were isolated from the dichloromethane and methanol extracts of Polygonum maritimum and identified as 2-hydroxy-4-[(2-methoxyethoxy)methoxy] acetophenone and 2-methyl-5-nonadecylresorcinol, respectively. In addition, 11 known compounds were identified, namely, the sesquiterpenoid (+)-8-hydroxycalamene, four ferulic acid esters (tetracosyl, hexacosyl, octacosyl, and triacontyl ferulate), the arylpropane broussonin B, the flavonoids quercetin, quercitrin, and (+)-catechin, the hydroquinone glucoside isotachioside, and beta-sitosterol. The structures of the new compounds were elucidated on the basis of their NMR and MS data. It is noteworthy that polygonophenone (1) is the first naturally methoxyethoxymethyl (MEM)-substituted natural product, and its isolation gives support for the use of MEM protection in biomimetic synthetic schemes.