Background An important aspect of Alzheimers disease (AD) is loss or impairment of cholinergic neurons. It is controversial whether there is a similar cholinergic impairment and cerebral deficit of acetylcholine (ACh) in the case of vascular dementia (VD). The purpose of this study was to explore the levels of ACh and choline (Ch) in the cerebrospinal fluid (CSF) of patients with AD and VD, and their possible relationship with cognitive impairment.Methods Twenty-two AD patients, twenty-two VD patients, and twenty normal controls were recruited and scored with a Mini-Mental State Examination (MMSE). CSF concentrations of ACh and Ch were measured using high-performance liquid chromatography with an electrochemical detector (HPLC-ECD) and the results were then compared to cognitive status.Results ACh concentrations in CSF of AD patients [(10.7±5.1) nmol/L] and VD patients [(16.8±7.4) nmol/L] were both significantly lower than in controls [(34.5±9.0) nmol/L, t=10.67, P