Manganese has been known to induce neurological disorders similar to parkinsonisms for a long time. Dopamine deficiency has been demonstrated in Parkinson's disease and in chronic manganese poisoning, suggesting that the mechanisms underlying the neurotoxic effects of the metal ion are related to dysfunction of the extrapyramidal system. However, the details of the mechanisms have yet to be elucidated. In an effort to learn more about the toxicity of manganese, we have employed an in vitro model that uses the PC12 catecholaminergic cell line. In this model, manganese induces apoptosis in PC12 cells. In this paper, experiments conducted with this model, the cellular biochemical changes, and the mechanism of the cell death are reviewed.