The diagnosis of neurodegenerative diseases with dementias requires several different test approaches and often remains uncertain. Using a proteomic approach it was shown in nine patients that heart fatty acid binding protein (H-FABP) might be a biomarker for Creutzfeldt-Jakob disease (CJD). The aim of our study was to evaluate whether H-FABP is a biomarker for the differential diagnosis of dementias. Therefore we measured H-FABP in cerebrospinal fluid (CSF) and serum of patients having CJD, dementia with Lewy-bodies (DLB), Alzheimer's disease (AD) and in non-demented control (NDC) patients. H-FABP levels in CSF and serum of CJD patients are increased compared to non-demented controls. Levels of H-FABP were significantly higher in CJD patients compared to AD and DLB in CSF. However, discrimination between CJD and AD was not possible in serum. Interestingly, highest levels of H-FABP were found in serum of DLB patients. Our results suggest that H-FABP might be a useful biomarker for the differentiation between the dementias examined if levels in CSF and serum are determined in parallel.