G₂ phase is a stage in the cell cycle, and is the final stage of interphase. It follows successful completion of DNA synthesis and chromosomal replication in S phase, and occurs during a period of time - often four to five hours. In this phase, the cell prepares itself for mitosis, or M phase, initiated by prophase.

At the end of this gap is another control checkpoint, the G₂ Checkpoint, to determine if the cell can now proceed to enter M mitosis and divide. The G₂ checkpoint prevents cells from entering mitosis when DNA was damaged since the last division, providing an opportunity for DNA repair and stopping the proliferation of damaged cells. Because the G₂ checkpoint helps to maintain genomic stability, it is an important focus in understanding the molecular causes of cancer.

Cell cycle