Vanadium (V) is a transition metal widely distributed in the environment. Occupational exposure to vanadium is common in oil-fired electrical generating plants and the petrochemical, steel, and mining industries. The International Agency for Research on Cancer (IARC) has classified vanadium as Group 2B, possibly carcinogenic to humans. Vanadium might cause apoptosis in some types of cells, but may be anti apoptotic in other types of cells. The exposure of some types of cells to vanadate resulted in generation of reactive oxygen species (ROS) and in activation of p53 activity - the most important apoptotic pathway induced by this metal. However, in some cell lines, the protein tyrosin phosphatase inhibitor sodium vanadate enhanced levels of protein tyrosine phosphorylation and it stimulated PI3K and its downstream kinase Akt/PKB that prevents apoptosis. It is not clear why vanadium is anti apoptotic in some types of cells, but pro apoptotic in other cells. The varying effects of vanadium on cell apoptosis may be due to the use of different forms of the metal, to the use of different doses of vanadium or to the different types of cells used in each experiment.