MicroRNAs are a class of endogenous, small, single-stranded, noncoding RNA molecules that regulate gene expression by promoting translational repression and/or degradation of target mRNAs through binding to their 3’untranslated regions. Since the first miRNA, lin-4, was identified in Caenorhabditis elegans approximately two decades ago, tens of thousands of miRNAs have been identified in various multicellular organisms, including humans, flies, nematodes, and plants, and deposited in the miRBase database . However, miRNAs in the goose have not been reported to date. There is increasing evidence that miRNAs play significant roles in various biological processes, including cell proliferation, differentiation, programmed apoptosis and cell death, morphogenesis of specific organs, and the pathogenesis of human diseases. Recent progress in understanding the biology and physiology of small RNAs has provided new and exciting perspectives on the regulation of reproductive function by miRNAs. A previous study showed that impaired ovarian corpus luteum angiogenesis in Dicerd/d mice was associated with a lack of miR17- 5p and let-7b, which participate in angiogenesis by regulating expression of the antiangiogenic factor tissue inhibitor of metalloproteinase . Recent research also indicates possible regulatory LY2157299 700874-72-2 effects of miR-196a on the expression of homebox genes in the newborn ovary that are associated with premature ovarian failure. Bta-miR-143, which has been reported to the most highly expressed miRNA in bovine testis and ovary, participates in pathways associated with reproduction. It is therefore conceivable that miRNAs play an important role in ovarian function. The goose is a commercially important food that is cultivated widely in China. However, the goose industry has been hindered by strong broodiness and poor egg-laying performance, which is strongly associated with ovary cyclical shinking in broody period. In this study, two sRNA libraries were generated from ovary tissues of laying and broody geese. We integrated the Solexa high-throughput sequencing technique and bioinformatics for sequencing and data processing to compare ovarian miRNA expression profiles between laying and broody goose and identify novel and differentially expressed miRNAs. Our miRNA data and expression profiling will promote better understanding of the functional involvement of miRNAs in the goose ovary. miRNAs are a class of small non-coding RNAs that function in gene regulation and play an important role in cell proliferation, maturation, and activity. The regulatory role of these sRNA molecules in the ovary has recently been explored in human, mouse, pig, cattle, sheep and goat; however, no systematic work has been conducted on the ovary of fowl, including goose. A few ovary miRNAs have been identified by computational and direct cloning approaches, but most goose ovarian miRNAs have not been identified or functionally studied. In this study, we created extensive miRNA profiles of ovaries from laying and broody geese.