Psychiatric symptoms were investigated and compared in 95 patients with Alzheimer type dementia (DAT) and in 39 patients with Parkinson's disease with dementia (PD-D). The diagnosis of the dementia and psychiatric disorders was based on DSM III R criteria; dementia stage was assessed using the Clinical Dementia Rating Scale (CDR). PD-D were significantly older than DAT patients. Delirium was more frequent in the advanced stages of both PD-D and DAT, being mainly of the hypoactive type in PD-D and the hyperactive type in DAT. Delusions and hallucinations predominated in the early CDR stages of both illnesses and did not differ between groups; the same was true for depression. The results revealed different psychopathological profiles in DAT and PD-D patients.