The spatial distribution of trace organic compounds in leachate plumes of two sanitary landfills was established by using multilevel sampling devices. The majority of the compounds originated from decomposing plant material and included aliphatic and aromatic acids, phenols, and terpene compounds. Minor constituents, including chlorinated and non-chlorinated hydrocarbons, nitrogen-containing compounds, alkylphenol polyethoxylates, and alkyl phosphates, were of industrial and of commercial origin. Vertical concentration profiles indicated accumulation of chlorinated solvents beneath the leachate plume. The distribution of trace organics at the two sites was much more complex than that of inorganics commonly used to map leachate plumes. This indicates that extensive monitoring will be required to predict future impacts.