Analysis of monoamine concentrations in brain tissue was carried out on the two types of Creutzfeldt-Jakob disease (CJD). The results showed decreased levels of catecholamines compared to control cases in a number of areas, and the reductions were most pronounced for dopamine. In general, the case classified as the amyotrophic form of CJD showed a greater degree of a monoamine loss than the case with spongiform encephalopathy, which is the typical transmissible form of CJD. These findings support the scarce available data indicating disturbances in the catecholaminergic systems in these types of brain diseases, and may have therapeutic implications.