For decades clinicians have postulated a characteristic preexisting personality in patients who develop Parkinson's disease (PD). They are described as moralistic, law-abiding, conscientious, and averse to risk-taking. The limited personality surveys tend to be confirmatory, but most of the literature is anecdotal or replete with unprovable psychodynamic postulates. In addition to an apparent stability of marriages and lack of alcoholism, patients with PD are less likely than controls to be smokers. It has been suggested that nicotine and its byproducts are not actually protective against PD, and it could be postulated that higher-than-average intrinsic dopamine may facilitate addiction. Smoking for the patient who is later to develop PD may be particularly unrewarding. In addition, the postulated personality for PD may predispose to hard work, perspiration, and increased exposure to putative trace elements in the water supply.