Cdc6 is an important player in cell cycle regulation. It is involved in the regulation of both S-phase and M-phase. Its role during oogenesis is crucial for repression of the S-phase between the first and the second meiotic M-phases, and it also regulates, via CDK1 inhibition, the M-phase entry and exit. This is of special importance for the reactivation of the major M-phase-regulating kinase CDK1 (Cyclin-Dependent Kinase 1) in oocytes entering metaphase II of meiosis and in embryo cleavage divisions, in which precise timing allows coordination between cell cycle events and developmental program of the embryo. In this chapter, we discuss the role of Cdc6 protein in oocytes and early embryos.