In this chapter we will describe in detail a method to identify the expression profile of miRNAs in developing vessels in zebrafish embryonic development using Illumina deep sequencing strategy. We will describe how to obtain RNA from FACS-sorted primary endothelial cells from growing vessels at early stages of development and how to prepare high-quality small RNA libraries using the TruSeq small RNA strategy for Illumina Hi-Seq machine. This methodology can be applied to discover and profile all forms of small noncoding RNA, including novel miRNA and sequence variants as well as quantification of miRNAs differentially expressed in endothelial cells during angiogenesis.