The purpose of this study was to develop an automated method for volumetric measurement of cerebrospinal fluid (CSF) in the sulci and lateral ventricles (LVs) based on three-dimensional (3-D) magnetic resonance (MR) images. The basic concept of our method is to extract the CSF spaces in the sulci and LVs separately in a brain by wrapping the brain tightly in a propagating surface determined with a level set method, which functions like as “plastic wrap.” The CSF spaces in the sulci and LVs were extracted by use of a logical XOR operation between the wrapped brain and the original segmented brain. We applied our method to high-resolution 3- D T1-weighted MR images of the whole brains obtained from 21 clinically diagnosed AD cases and 16 non-AD cases. As a result, CSF spaces in the sulci and LVs were extracted well separately. The mean volume ratios of CSF in LVs to a whole brain for AD patients and non-AD cases were 0.0496 and 0.0301, respectively, which indicated a significant difference (p < 0.01) by Student t test, and the ratios for sulci were 0.197 and 0.164, which also indicated a significant difference (p < 0.005). Our preliminary results showed that our method may be promising for measuring the CSF volumes.