This　study　is　to　investigate　the　presence　of　brain　gray　matter　abnormalities　in　young　onset　essential　tremor　(ET)　patients　with　arm　tremor.　Thirty　ET　patients　together　with　30　healthy　volunteers　were　taken　as　candidates.　Magnetic　resonance　imaging　(MRI)　was　performed　and　voxel-based　morphometry　was　used　to　compare　gray　matter　density　between　the　patients　and　volunteers.　Washington　Heights-Inwood　Genetic　Study　of　Essential　Tremor　(WHIGET)　rating　scale　was　applied　to　assess　tremor　severity　in　the　patients.　Eventually　Twenty-Seven　ET　patients　and　Twenty-Seven　volunteers　were　enrolled　in　the　study.　Voxel-based　morphometry　showed　significant　expansion　of　the　bilateral　cerebellum,　occipital　fusiform　cortices,　right　inferior　temporal　gyrus,　and　precentral　lobes　(P ＜ 0.05,　TFCE　corrected).　Decrease　in　gray　matter　was　detected　only　in　the　left　parietal　lobe.　Region　of　interest　analysis　showed　volume　enlargement　in　thalamus,　midbrain,　and　precuneus　(P ＜ 0.05,　TFCE　corrected).　Importantly,　significant　negative　correlation　was　found　between　the　lateralized　index　of　cerebellum　and　the　tremor　score　which　might　implicate　that　the　altered　rightward　lateralization　in　the　cerebellum　is　possibly　a　response　of　the　tremor　effects　in　ET　patients.　Cerebellar　gray　matter　expansion　in　young　onset　ET　patients　with　arm　tremor　might　be　the　result　of　compensation　towards　decline　of　cerebellar　function.