Metal welding produces gaseous fumes that contain manganese, resulting in potential occupational exposure to welders. It has been hypothesized that occupational exposure among welders could increase risk of Parkinson's disease and other neurodegenerative diseases. The present study examines welding occupation and mortality from neurodegenerative diseases among men in the United States using the National Cause of Death databases 1985 to 1999. Information was abstracted from death certificates for states that collected data on occupation. Of 4,252,490 men who died during the study period, 107,773 had welding-related occupations. Multivariable logistic regression models were used to calculate mortality odds ratios (MOR) and 95% confidence intervals (CI) for odds of dying from Parkinson's disease or other neurodegenerative diseases among men who were welders as compared with men of other occupations, adjusting for attained age, race, region of residence, and year of death. During the study period, 49,174 deaths were attributed to Parkinson's disease, 54,892 to Alzheimer's disease, and 19,018 to presenile dementia. There was no evidence of an increased odds of Parkinson's disease mortality among welders as compared with men with other occupations (MOR = 0.83, 95% CI 0.78-0.88). Furthermore, welding occupation was unrelated to the odds of mortality from Alzheimer's disease (MOR = 0.94, 95% CI 0.89-1.00) or presenile dementia (MOR = 0.96, 95% CI 0.87-1.06). Earlier research suggested that welding exposures could predispose individuals to earlier onset Parkinson's disease. However, there was no evidence in this data of an increased mortality odds ratio associated with welding occupations among men younger than 65 (MOR = 1.03, 95% CI 0.74-1.44); while there was a suggestion of a lower odds Parkinson's disease death among men age 65 years and older (MOR = 0.82, 95% CI 0.77-0.88). Data from this large study do not support an association between welding occupations and death from Parkinson's disease or other neurodegenerative diseases, nor that welders are at increased odds of dying from Parkinson's disease at a younger age.