4,4'-Dihydroxytruxillic acid (DHTA) and 4,4'-dihydroxy-3,3'-dimethoxytruxillic acid (DHMTA), photodimers of p-coumaric and ferulic acids, respectively, as well as p-coumaric, ferulic, caffeic, hydroxyferulic and sinapic acids, were identified as components of the cell walls of stems and leaves of bamboo (Phyllostachys edulis) and bamboo grass (Sasa kurilensis). The amounts were determined by measurement of peak areas using GC-MS with 1-octadecanol as internal standard.