undertake such interlaboratory comparisons with sediment samples in the future, especially as new methods are developed and applied to environmental analyses. Such studies are needed to determine when different numbers generated by different laboratories using different methods are environmentally significant.If nothing else, the results of this intercomparison study should serve as a warning against overinterpretation of currently generated trace-level hydrocarbon determinations. The results should not be used as an argument against further intercomparison exercises, but should be used as encouragement for the continued development of the state-of-the-art of trace organic analysis. Ultimately, the goal of the National Bureau of Standards is to produce a Standard Reference Material with certified trace-level concentrations of environmentally significant organic compounds in a "real" matrix. Unfortunately, methods for preparing and certifying such a material have not yet been developed. Problems associated with sample homogeneity, stability, matrix effects, etc. must also be resolved before any such standard can become available. The low concentration of hydrocarbons anticipated in many pollution baseline studies necessitates the development of sensitive analytical techniques. Finally, some form of information exchange or intercomparison must exist among laboratories in order to assess the uncertainty of the data from these new analytical techniques.