To gain insight into the neural pathways involved in the pathogenesis of DYT1 dystonia, we have mapped the cellular expression of the mRNA encoding torsinA and the closely related family member, torsinB, in normal adult human brain. Here, we report an intense expression of torsinA mRNA in the substantia nigra pars compacta dopamine neurons, the locus ceruleus, the cerebellar dentate nucleus, Purkinje cells, the basis pontis, numerous thalamic nuclei, the pedunculopontine nucleus, the oculomotor nucleus, the hippocampal formation, and the frontal cortex. Within the caudate-putamen, the cellular expression of torsinA mRNA was heterogeneous; a moderate signal was found overlying large cholinergic neurons, and most striatal neurons exhibited only a very weak signal. A moderate signal was detected in numerous midbrain and hindbrain nuclei. A weak cellular signal was detected in neurons of the globus pallidus and subthalamic nucleus. In marked contrast to torsinA, no specific mRNA signal was detected for torsinB. That torsinA mRNA is enriched in several basal ganglia nuclei, including the dopamine neurons in the substantia nigra, is intriguing since it suggests that DYT1 dystonia may be associated with a dysfunction in dopamine transmission.