Tremor and parkinsonism are recognized side effects of valproate; however, the 
relationship between rest tremor and other signs of parkinsonism has not been 
addressed in patients taking valproate. We studied a cohort of 125 consecutive 
patients treated with valproate due to epilepsy or migraine, evaluated with the 
Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS). A total of 14 (11.2%) patients 
had rest tremor (bilateral n = 10, unilateral n = 4). Patients with rest tremor 
had significant higher scores in the FTM-TRS (P < 0.001), but only one was 
diagnosed with parkinsonism. Patients may have valproate-induced parkinsonism or 
exacerbated motor features of Parkinson's disease by valproate. The frequency of 
parkinsonism was 1.6% in this cohort and of 3% in the pooled data of 717 
patients from previous reports. Rest tremor is observed in 11.2% of patients 
treated with valproate and is related to the burden of valproate-induced tremor, 
rather than the presence of parkinsonism.