c-fos is a protooncogene serving in multiple physiological processes in brain from signalling to proliferation and synaptic plasticity. We therefore decided to determine this transcription factor in control and Down Syndrome (DS) brain with the Rationale that c-fos may be linked to brain damage in DS. We determined mRNA steady state levels in frontal, parietal, occipital, temporal cortex and cerebellum of 9 patients with DS and 9 controls using RT-PCT. Significantly increased levels of mRNA c-fos normalized versus the housekeeping gene beta-actin mRNA were found in frontal, parietal and temporal cortex of DS brain. c-fox mRNA levels comparable to controls were found in occipital cortex and cerebellum. Deteriorated c-fos expression in the individual brain regions may be linked to increased apoptosis and neurodegeneration, overexcitation by excitatory amino acids of reactive oxygen species.