PURPOSE: SIR proteins (silent information regulators, sirtuins, SIRT1 - SIRT7, SIR1 - SIR7) belong to NAD+-dependent deacetylases, enzymes taking part in a catalytic reaction of deacetylation, i.e. splitting the rest of acetic acid from protein substrates. Sirtuins play an important role in many cellular processes and are, therefore, involved in the ageing process and in the regulation of cell life. The aim of this paper is to verify the statistical hypothesis assuming the correlation between the age and level of education of examined persons and the expression of selected sirtuins (SIR1 - SIR7, SIRT1 - SIRT7) at the mRNA level in the Polish population. MATERIAL AND METHODS: 197 people, aged M = 38.27 (SD = 13.19), in whom expression at the level of mRNA for SIR1 - SIR7 was determined, took part in the study (99 healthy people with a negative history of mental and somatic diseases and 98 people with diagnosed recurrent depressive disorders). RESULTS: A significant correlation was found in the case of age of the examined individuals and the expression of SIR1 - SIR7 at the mRNA level (p < 0.001). Differences in the expression of SIR1 - SIR7 were also found in relation to the level of education (number of years of education) of the examined population (p < 0.001). CONCLUSIONS: 1. The higher the number of years of education, the higher the level of SIR1 and SIR6 expression, and the lower the level of SIR2, SIR3, SIR4, SIR5 and SIR7 expression. 2. With age, the level of SIR1 and SIR6 expression decreases and the expression of SIR2, SIR3, SIR4, SIR5 and SIR7 increases.