Polyamines (PAs) are an essential class of metabolites found throughout all kingdoms of life. They are derived from amino acids, intestinal bacteria, exfoliated enterocytes and supported from diet. They are the key compounds that play crucial role in cell proliferation, growth and differentiation. They also exert significant effects on embryonic development, implantation, embryonic diapause, placentation, angiogenesis and fetal development. Therefore, we discuss their functions, synthesis, sources and future prospects of polyamines.