The human body is made up of millions of cells of different types. The cells originate from a single cell in the mother’s womb as a result of fertilization that takes place between the mother’s ovum and the father’s sperm. This first cell (the zygote) then starts to divide and the cells produced as a result of numerous rounds of cell division differentiate to eventually form the complete human body. Formation of the reproductive cells (the ovum and the sperm) is via the process of meiosis and somatic cell division to form the complete body is via mitosis. The phases that a cell undergoes from the time it is formed to the time it divides itself is called the cell cycle. It includes the preparatory phase, the synthesis phase and the division phase (mitosis or meiosis). The cell cycle is meticulously regulated to ensure that only those cells that need to divide and are able to do it normally (either mitotically or meiotically) do so with the right timing. Failure of this regulation due to mutation could lead to grave consequences e.g. hereditary diseases and cancer. In this Module, we will discuss the cell cycle, mitosis, meiosis (spermatogenesis and oogenesis), and regulation of the cell cycle that ensures precise cell division. We will also explore the consequence of mutation and cell cycle dysregulation e.g. development of cancer.