Several trench leachate samples collected from commercially operated low-level radioactive waste disposal sites at Maxey Flats, Kentucky and at West Valley, New York were analyzed for organic constituents. The organic compounds in the water samples were extracted with methylene chloride, separated into acidic, basic, and neutral fractions, and analyzed by gas chromatography and mass spectrometry. About 75 compounds consisting of several straight and branched chain aliphatic acids, aromatic acids, alcohols, aldehydes, ketones, amines, aromatic hydrocarbons, esters, ethers, and phenols were identified in the leachate samples. These compounds represent, in general, the synthetic and natural organic wastes such as contaminated cellulosic materials, scintillation liquids, solvents, and decontamination fluids buried in the trenches and their biological decomposition products. The organic compounds, especially the organic acids, phthalates, and tributyl phosphate, may influence the mobility of the radionuclides from the burial trenches by solubilization, leaching, and formation of weak complexes.