BACKGROUND AND PURPOSE: McLeod neuroacanthocytosis syndrome (MLS) is an X-linked multisystem disorder with CNS manifestations resembling Huntington disease. Neuroimaging studies revealed striatal atrophy with predominance of the caudate nucleus. Our previous cross-sectional MRI study showed an association of volume loss in the caudate nucleus and putamen with the disease duration. METHODS: In the present study, we examined three brothers with genetically confirmed diagnosis of MLS using an observer-independent and fully automated subcortical segmentation procedure to measure striatal volumes. RESULTS: In a cross-sectional comparison with 20 healthy age-matched control men, the volumes of the caudate nucleus of the three patients were significantly smaller as confirmed by z-score transformations. On an individual basis, volumes in the two more severely affected and older patients were smaller than in the less affected younger brother. Longitudinal MRI-based measurements over 7 years demonstrated a statistical trend towards significant decreased caudate volumes in McLeod patients. CONCLUSIONS: Our findings indicate that structural MRI combined with fully automated computational morphometric analyses represents an objective and observer-independent imaging tool for the representation of progressive striatal degeneration in MLS and might be a valuable methodology for cross-sectional as well as longitudinally volumetric studies in other rare neurodegenerative diseases, even on individual patients.