Studies of late stages of Parkinson's disease (LS-PD) are limited. To provide an adequate health plan for patients in these most advanced stages, accurate information on their clinical condition is necessary. We characterize clinical features and medication use of LS-PD. A cross-sectional study of LS-PD stage 4 or 5 of Hoehn and Yahr during on states is presented in this paper. Demographics, clinical features and medication data were obtained using a structured questionnaire and physical examination. Patients were asked to grade the perceived impact of symptoms on their health status. Fifty patients (mean age 74.1 years and mean disease duration 17.9 years) were studied. Severe akinetic symmetric parkinsonism was present in most, with negligible rigidity and tremor, and most patients were wheelchair-bound. Severe postural instability and freezing of gait, causing frequent falls and fractures, and prominent dysarthria and dysphagia dominated the motor syndrome. Levodopa remained effective in most patients in relieving motor symptoms including tremor. Motor fluctuations and dyskinesias were present in 78 and 62% of patients, respectively, but were not perceived as disabling. All had neuropsychiatric and dysautonomic symptoms. Visual hallucinations were present in 44%, depression in 62% and dementia in 50%. Lack of tremor (p < 0.01) and absence of depression (p < 0.01) were independently associated with dementia (R(2) = 45%). Symptoms causing greatest impact on perceived health status were falls, gait unsteadiness, urinary dysfunction and sweats. Motor and non-motor non-levodopa responsive problems were frequent and the main cause of disability. Fluctuations and dyskinesias were frequent though not disabling. Dementia is not unavoidable in these very late stages.