A fatal case of suicidal ingestion of the herbicide endothall (7-oxabicyclo2,2,1heptane-2,3-dicarboxylic acid) is described. Endothall was determined after initial phophotungstic acid deproteination followed by extraction using 1,2-dichloroethane:tert-butanol(2:1) and subsequent injection into the gas chromatograph equipped with a flame ionization detector. Identity was confirmed by thin-layer chromatography, infared spectrophotometry, and gas chromatography/mass spectrometry. 12 refs.