The Sydney rock oyster, Saccostrea glomerata, has been demonstrated as a useful biomonitor of estrogenic compounds following laboratory exposures, yet its utility in the assessment of estrogenic exposure and effects under field conditions requires investigation. To achieve this aim, S. glomerata were deployed in Newcastle, Australia in the effluent receiving marine waters of Burwood Beach WWTP (Burwood Beach "near", <50 m from outfall and Burwood Beach "far", 100-150 m from outfall) and reference locations (Redhead, Fingal Island 1 and Fingal Island 2) at depths of 4, 8 and 12 m for six weeks. Effluent receiving waters of Burwood Beach WWTP were found to be a suitable impact location, demonstrated via measurement of estrogenic compounds and activity throughout the deployment. Estrogenic compounds were detected (average of combined solids and liquid fractions) at average concentrations of: 1.42 ng/L for estrone, 0.69 ng/L for 17β estradiol, 3.83 ng/L for estriol (E3), 0.56 ng/L for 17α-ethynylestradiol, 64.2 ng/L for bisphenol A, 7.51 ng/L for 4-nonylphenol and 5.93 ng/L for 4-tert-octylphenol. Total estrogenic activity was estimated at 4.48 ng/L EEQ via the Yeast Estrogen Screen (YES(®)) assay (average of combined solid and liquid fractions). Female vitellogenin gene expression was highest at Burwood Beach locations, yet no significant differences were detected among locations for either sex. Vitellogenin protein was significantly higher (p<0.05) in S. glomerata at Burwood Beach Near compared to reference locations for the 4 and 12 m depths. Increased proportions of females were found at Burwood Beach Near, at 4m depth (p<0.05). Both Burwood Beach locations had higher proportions of mature female gonadal development stages compared to reference locations (p<0.05). Oocyte area was highest at both Burwood Beach locations, but no significant differences were detected among locations. Findings provided further evidence that female S. glomerata may be a suitable candidate species for assessment of effects of estrogenic compounds in Australian waters.