Homocysteine (Hcy) has recently become the focus of interest in the research on Parkinson's disease (PD) and other neurodegenarative disorders. Chronic treatment with levodopa (LD), considered the standard treatment for PD, leads to an increase in homocysteine concentration in serum and cerebro-spinal fluid. Independently from this effect, homocysteine is also regarded as a marker of neurodegenerative disorders. Main interest was focused on hyperhomocysteinemia (hHcy) as the potential risk factor for atheromatosis. Subsequently, its role in neuropsychiatric diseases, e.g. depression, mild cognitive impairment and dementia was investigated. The potential pathogenic role of Hcy in peripheral neuropathy in patients with PD that are treated with LD is an interesting hypothesis but the literature is scarce. Confirmation of this association may lead to introduction of preventive therapies, e.g. administration of vitamin B and inhibitors of catechol-O-methyl transferase (COMT) that may decrease the Hcy blood concentrations.