The National Oceanic and Atmospheric Administration (NOAA) established the National Status and Trends (NS and T) Mussel Watch Project in 1985 to assess the current status and the long term trends for selected contaminants in US coastal waters. Starting in 1994 bivalves have been analyzed for compounds not reported in previous years. Dicofol, alachlor, trifluralin and atrazine were detected in 5% of the samples and analyses were not continued. On the other hand, the concentrations of 1,2,4,5-tetrachlorobenzene, 1,2,3,4-tetrachlorobenzene, pentachlorobenzene, pentachloroanisole, endosulfan and chlorpyrifos were measurable in bivalves collected from 1994 to 1997. The distribution of concentrations for these analytes were different from each other and from the pesticides, polycylic aromatic hydrocarbons and polychlorinated biphenyls historically measured in the NS and T project. The concentrations of these analytes are comparatively low and some were not detected at a majority of sites sampled. However, continued monitoring will provide information on the temporal trends of these environmental contaminants and therefore should be continued.