Nonylphenol and octylphenol have been identified as endocrine disrupters with the ability to cause reproductive deformities in a number of organisms. A normal phase high-performance liquid chromatography (HPLC) method with fluorescence detection was developed with a mobile phase of cyclohexane/methyl-tertiary-butyl ether (MTBE) (70 + 30). The extraction of the alkylphenols from the water samples was evaluated using solid-phase extraction (SPE) with a C2 packing sorbent. The complete method was validated and the limit of detection calculated to be 0.15 ppb (microg l(-1)). The method was novel for the analysis of specific alkylphenols in an aqueous matrix. A survey of the Forth Estuary in May 2000 resulted in no detectable amounts of nonyl- or octylphenol, whilst a survey during August of the same year produced concentrations ranging from 0.17-1.90 ppb for nonylphenol and 0.17-1.28 ppb for octylphenol. These results are compared with other river and estuarine studies with concentrations considered in terms of toxicity to aquatic organisms. The concentrations determined in the Forth Estuary are consistent with a contaminated though not grossly polluted estuarine system.