In the Corpus geniculatum laterale [pars dorsalis] (Cgl d) of the rat the distribution of the following enzymes is described on the light microscopical level: acid phosphatase, nonspecific esterases, Thiaminepyrophosphatase (TPPase), cholinesterases (AchE and ChE), GABA-alpha-ketoglutarat-transaminase (GABA-T), monoaminooxidase (MAO) and leucin-aminopeptidase. The acid phosphatase and TPPase are localized in the pericarya of different cell types of the Cgl d. The nonspecific esterases are present intracellularly and in the neuropil. With the GABA-T-reaction single cells of Cgl d are stained. The leucine aminopeptidase could not be demonstrated in the Cgl. The nonspecific cholinesterase is localized in the vessel walls. AChE and MAO are present in different fiber structures in the Cgl. Electron microscopical investigations of AChE showed a localization of the enzym in the extracellular room, intraaxonal and in the synaptic cleft. Separation of ChE in polyacrylamid gel resulted in 2 bands for the AChE and 1 band for the nonspecific ChE. After left side enucleation the reaction of the enzymes acid phosphatase, nonspecific esterases cholinesterases and TPPase was proofed topochemically at the section and biochemically at the homogenate. A decrease of enzyme activity in the enzymes acid phosphatase, nonspecific esterases and AchE is shown. The alterations are discussed in connection with the transneuronal degeneration.