Nonylphenols (NPs) have been identified as xenoestrogens and have been found at high concentrations in Canadian and European biosolids. While nonylphenol polyethoxylates (NPEOs) are being phased out and regulated in several European countries, there is currently no regulation of these compounds in the United States, and little information is available concerning the presence of NPs in U.S. biosolids. Anaerobically digested sewage sludge from five wastewater treatment plants in central New York State was analyzed for the presence of NPs. Samples were taken from treatment plants in both small municipalities and larger metropolitan areas with a range of industrial inputs. Samples were extracted via Soxhlet apparatus and analyzed by GC/MS. The various isomers of NP were summed yielding total NP concentrations as high as 1840 mg/kg with a mean of 1500 mg/kg on a dry weight basis. These values are two to five times as high as previously reported concentrations for U.S. and Canadian biosolids from plants using similar treatment schemes.