Nonylphenol (NP) and octylphenol (OP) have been identified as potential endocrine disrupters with the ability to induce reproductive deformities in a number of organisms. The main source of these compounds into the aquatic environment is through industrial and sewage effluent discharge. A method for their analysis has been developed making use of normal phase high performance liquid chromatography coupled with fluorescence detection. The extraction of these compounds from river and estuarine water was developed using solid phase extraction with a C₂ packing sorbent. The complete method was validated using spiked de-ionised water and the limit of detection calculated to be 0.13 μg/1 (ppb). A survey of the Forth Estuary in May 2000 found alkylphenol concentrations to be below the limit of detection though the results from a survey carried out in August of the same year produced concentrations ranging from < 0.13-1.90 μg / 1 for nonylphenol and < 0.13-1.28 μg /1 for octylphenol. Concentrations of nonyl- and octylphenol have been determined for suspended solids and sediment from the Forth Estuary. NP and OP from the solid material was extracted into iso-hexane over a period of 6 hours using soxhlet apparatus. The extract was subject to solid phase extraction using an amino packing sorbent prior to analysis. The limit of detection for the sediment method is calculated to be 10.2 μg / kg (ppb) for both NP and OP. The surveys of the Forth Estuary for both May and August produced sediment results ranging from < 10.2-152 μg / kg for nonylphenol and < 10.2-87.4 μg / kg for octylphenol. The limit of detection for the suspended solid work is calculated to be 0.08 μg / 1 (ppb). The resulting concentrations from the May and August survey are 0.09-0.26 μg / 1 for nonylphenol and < 0.08-0.26 μg / 1 for octylphenol. The results are consistent with a river estuary that is contaminated, though not grossly polluted by NP and OP. Although these results show NP and OP to be below toxicity thresholds for many aquatic organisms, the scope for their bioaccumulation within aquatic species means a chronic, rather than acute impact from NP and OP inputs might be anticipated.