BACKGROUND: Dementia with Lewy bodies (DLB) is the second common degenerative dementia and has several characteristics including fluctuating cognition, visual hallucination and parkinsonism. We investigated clinical manifestations, responsiveness to drugs and neuroimaging findings in DLB patients. METHODS: Ten probable DLB patients were included in this study. For responsiveness to drugs, we measured Unified Parkinson's Disease Rating Scale (UPDRS) of rest tremor, rigidity and bradykinesia (finger tapping and leg agility), and Korean version of mini-mental state examination (K-MMSE) before and after administration of levodopa or cholinesterase inhibitors. Brain MRI, cerebral perfusion SPECT (Tc-99m HMPAO) and dopamine transporter SPECT (123I-IPT) were also performed. RESULTS: All patients were men and mean age of onset was 66.9 years (range from 58 to 80). All had fluctuating cognition and parkinsonism, and 7 had visual hallucination. Mean increment of K-MMSE after administration of cholinesterase inhibitors was 2.1 points. Levodopa reduced UPDRS scores of tremor, rigidity and bradykinesia by 0.4, 0.6 and 1.0 points, respectively. Cerebral perfusion SPECT using Tc-99m HMPAO showed hypoperfusion in occipital area as well as fronto-temporoparietal areas. Dopamine transporter SPECT using 123I-IPT revealed reduced uptake comparable to Parkinson's disease in the striatum. CONCLUSIONS: DLB should be first considered as one of possible diagnoses in patients showing dementia in the early stage of parkinsonism. Responsiveness of parkinsonism to levodopa seems favorable. Cholinesterase inhibitors are thought promising in enhancing cognition in short term periods. It is suggested that occipital hypoperfusion be a characteristic finding in DLB and be helpful in differentiating DLB from other degenerative dementias.