Background: The prevalence of the peripheral neuropathy (PN) is of 4.2 – 8% in those over 65 y.o. In patients with the Parkinson’s disease (PD) a PN – prevalence of 34.2 – 55% was reported. Low vitamin B12-blood level was present in 13% of PD patients. There is a higher prevalence of PN in levodopa-treated patients (36.1%) than in naive (12.1%) and in healthy controls (8.1%). Material and methods: We examined 601 patients with PD. Of them, 407 patients underwent electrophysiological examination. Results: 444 (73.9%) had clinically PN. Of 407 patients who underwent electrophysiological investigations, in 361 (88.7%) PN was confirmed. The most common was axonal (304 patients; 84.2%), sensory (282; 78.1%), and slight (78; 21.6%) or moderate (164; 45.4%) PN. Of 471 patients receiving levodopa, 369 (78.3%) had clinical PN, compared to 75 (56.8%) of 132 levodopa-naive patients (p<0.01). At the T1 – time – point of first – diagnosis of polyneuropathy, 179 patients (40.3%) of 444 with PN had a vitamin B12-deficiency. In 585 of patients, 38 (33.3%) of 114 levodopa-naive PD patients had vitamin B12-deficiency at the T1, compared to 129 (27. 1%) of 471 levodopa-treated PD patients (p=0.2). Conclusions: Peripheral polyneuropathy is very common in PD. In our group of PD patients the prevalence of a clinical polyneuropathic syndrome was very high and in almost 90% of cases it was confirmed electrophysiologically. 40% of patients with PN had a vitamin B12 deficiency. Levodopa-treatment was more common in PD patients with PN than in those without.