An autopsy case of unclassifiable presenil dementia is reported. The outstanding pathological findings were as follows; 1. presence of senile plaques, neurofibrillary changes, Pick bodies, Hirano bodies, granulovacuolar degeneration of neurons, etc. 2. numerous Lewy bodies in the brain stem and diencephalon, 3. peculiar swollen neurons with intracytoplasmic, eosinophilic and argentophilic inclusions ("Lewy-like-bodies") in the cerebral cortices. Detailed study of the last mentioned inclusions indicates that they are almost identical to Lewy bodies, though there are some minor differences, in histochemical and electronmicroscopic findings. Nosologically, this case may represent either a combination of Alzheimer's disease, Pick's disease and idiopathic Parkinsonism with "Lewy-like-bodies" in the cerebral cortices, or a single disease. As far as we know, no similar case been reported.