Dementia with Lewy bodies is considered to be the second most common, after Alzheimer’s disease, cause of primarily degenerative dementias. Dementia with Lewy bodies, despite being quite common (according to epidemiological and clinicopathological studies), is still relatively rarely diagnosed in general practice. Wrong diagnoses of Alzheimer’s and Parkinson’s diseases are the commonest diagnostic errors, psychosis (usually attributed solely to aging process) being an alternative. Incorrect diagnosis results in ineffective treatment, and because of hypersensitivity to even small doses of antipsychotic drugs in DLB cases, treatment often could be extremely dangerous. Differential diagnosis includes differentiation with other primarily neurodegenerative dementias, including the closest phenotypically – Alzheimer’s disease with parkinsonism and dementia in Parkinson’s disease. Differentiation and giving of the correct diagnosis facilitates the use of clinical diagnostic criteria and additional tests. The most important issue is finding the characteristic clinical picture of psychiatric and neurologicalpresentation and the sequence of the onset of dementia and parkinsonism. Optimal improvement in majority of patients is possible with correct diagnosis and the use of strategies from the border of neurology and psychiatry. Cholinesterase inhibitors are mainstream treatment option for cognitive dysfunction (also some behavioural improvement, psychosis included, might be achieved) while levodopa is used for motor symptoms control. Antipsychotics must be used very cautiously and the first-line choice is currently quetiapine. An important issue is the treatment of coexisting REM-sleep disorder and autonomic dysfunction.