The effects of dietary estradiol-17 (E₂) on growth and liver transcriptomics were investigated in the yellow perch (Perca flavescens). Following a 3 month treatment, E₂ significantly stimulated an increase in length and weight of juvenile male and female perch relative to controls. The increase was significantly greater in females as compared to males. Separate, un-normalized cDNA libraries were constructed from equal quantities of RNA from 6 male and 6 female livers of E₂-treated and control perch, and 3,546 and 3,719 ESTs were obtained, respectively. To characterize E₂-regulated transcripts, EST frequencies between libraries were calculated within contiguous sequences that were assembled from the combined ESTs of both libraries. Frequencies were also determined in EST transcript groupings produced by aligning all of the ESTs from both libraries at the nucleotide level. From these analyses, there were 28 annotated transcripts that were regulated by 75% between libraries and for which there were at least 5 ESTs of the same transcript between libraries. Regulation of a subset (14) of these transcripts was confirmed by quantitative reverse transcription - polymerase chain reaction (QPCR). Transcripts that were upregulated by E₂ included reproductive-related proteins, binding proteins, and proteases and protease inhibitors. While not part of the transcript frequency analysis, QPCR showed significant upregulation of estrogen receptor esr1 and of insulin-like growth factor 1 (IGF-1) in E₂ livers. E₂-downregulated transcripts represented a variety of functional categories including components of the respiratory chain, lipid transport and metabolism, glycolysis, amino acid and nitrogen metabolism, binding proteins, a hydrolytic enzyme, and a transcriptional regulator. In perch it appears that exogenous estrogen drastically shifts liver metabolism towards the production of lipoproteins and carbohydrate binding proteins, and that the growth promoting action may involve an increase in hepatic IGF-1 production.