Microarrays are used to assess the impacts of aquatic contaminants in both laboratory and field studies, which necessitates the validation of the comparability of microarray data generated by different laboratories before this tool is adopted for regulatory toxicology or environmental monitoring. Fundamental issues which need answering before microarray technology can be used in environmental monitoring programs include defining whether these molecular changes translate into adverse effect at the individual or population level, as well as how large a magnitude (threshold) and how to quantify (fold change versus p value) a modification or modifications in gene expression which constitute an adverse effect. Here, male FHM were exposed to 25 ng/L EE2 for 96 hr, and six laboratories received flash frozen liver to conduct a microarray analysis on using a 60K Agilent microarray. This study aimed to assess the congruency of microarray data across six independent laboratories given both control and EE2 exposed samples, and to identify gold standard estrogen-responsive genes triggered by treatment with an environmentally relevant EE2 dose. 8 biological replicates per group. 2 groups, control and EE2 treated.