In order to evaluate the effect of dementia on survival in Parkinson 's disease (PD), we followed a series of 250 PD over a period of 5 years. Dementia was determined according to DSM-III-R criteria. Survival analysis of PD patients with dementia vs. without dementia was performed using entry date as starting point. Cox model was used for evaluation of variables associated with mortality in this sample. Upon inclusion to the study, dementia was diagnosed in 38% of our patients. At the end of the follow-up period, the cumulative death rates were 39% among the demented patients and 34% among the non-demented ones (chi(2)=3.2, df=1, p=0.07). Advanced age and, but marginally, cognitive deterioration were associated with reduced survival [Exp(beta)=3.4, p=0.005 and Exp(beta)=1.3, p=0.06, respectively].