The understanding of the early mammalian development is a prerequisite for the advancement of in vitro fertilization and improvement of derivation and culturing of embryonic stem cells. While, whole genome transcriptomic analysis on bovine blastocysts has identified genes active in early development, little information is available about the protein complement of early embryos. Modern, sensitive proteomic technology (nano HPLC tandem mass spectrometry) allowed us to describe the proteome of the scarce blastocoel fluid and cell material of expanded bovine blastocysts isolated by micromanipulation. From two independent replicates, 23 proteins were identified in the blastocoel fluid while 803 proteins were identified in the remaining cell material. The proteins were grouped into categories according to their gene ontology (GO) terms by which proteins involved in cell differentiation, cell proliferation, development, and reproduction could be derived. Proteins classified in these categories could be candidates for further functional studies to understand pluripotency and early mammalian development.