Statistical surveys have shown that the dairy farm industry alone contributes to over 90% of the total estrogen released into the environment in the UK and US. Constructed wetland systems (CWSs) have been used as a low cost bio-filtration system to treat farm wastewater. While studies have shown that CWSs are efficient in removing organic contaminants and microbes, there is limited data on the presence of hormones in this type of treatment system. Analysis of hormonal levels and activity was performed using reporter gene assays (RGAs) which incorporate relevant receptors capable of measuring total androgenic or estrogenic loads. The assay was highly sensitive and capable of detecting compounds with estrogenic and androgenic bioactivity at concentrations as low as 0.009mg/ml and 0.36ng/ml, respectively. Monthly sample analysis revealed the presence of both androgenic activity with max 598 ng L-1 testosterone equivalents (TEQs) and estrogenic activity with max 100.6 ng L-117β-estradiol equivalents (EEQs) in the Greenmount CWS. Our results demonstrate that Greenmount CWS is an efficient system for the treatment of hormonal contaminants in dairy farm wastewater by significantly reducing androgenic levels by 94.75 % and estrogenic levels by 91.38%.