During aging many of the brain functions became deteriorated or altered. One of the most important age related changes is an increase of anxiety level, reported both in humans and in animals. Our study was intended to compare c-fos gene expression in amygdala, the key structure in anxiety/fear regulation, in old (24 months) and young (4 months) rats exposed to various behavioral stimulations. There were no differences between age groups in basal c-Fos expression. After social encounter c-Fos expression level in amygdala increased significantly, but still remained independent on age. Significant differences between both groups appeared after open field test and immobilization test. Contrary to the findings on young adults indicating the correlation between increased anxiety level and higher c-Fos expression, old rats showed increased anxiety together with significantly lower c-Fos expression.