Until there is a greater understanding of basic tremorgenic mechanisms in the central nervous system, current classifications of tremors rely heavily on the behavioural characteristics, putative sites of origin, and/or the underlying disease process. Careful clinical evaluation remains the centrum of tremor classification. Few tremors do show specific neurophysiological features that will clinch diagnosis, e.g., primary orthostatic tremor and dystonic tremor. With the exception of dopaminergic drugs in Parkinson's disease, drug effects in tremors are unpredictable and nonspecific. Drug side effects should be considered in the differential diagnosis of any unexplained tremor.