Excessive manganese exposure may induce a neurological syndrome called manganism, which is similar to Parkinson's disease (PD). However, close observation of patients with manganism reveals a clinical disease entity different from PD, not only in the clinical manifestations, but also in therapeutic responses, in neuroimaging studies such as magnetic resonance imaging, positron emission tomography and dopamine transporter images, and in the neuropathological findings. Furthermore, after long-term follow-up studies, patients with manganism showed prominent deterioration in the parkinsonian symptoms during the initial 5-10 years, followed by a plateau during the following 10 years, which is also different from the clinical course of patients with PD. Although typical patients with manganism are different from patients with PD, the potential risk of inhaling welding fumes, which may accelerate the onset of PD or even induce PD, has been raised during recent years. This controversial topic requires further investigation.