Theory of mind (ToM) refers to the ability to attribute independent mental states, such as beliefs, preferences and desires, to the self and others. Neuroimaging studies of normal adults have consistently demonstrated the importance of particular brain regions for ToM, the superior temporal sulcus (STS), temporal pole (TP) and the medial prefrontal cortex (MPFC). However, there are little data showing how ToM develops during childhood and adolescence. Such data are important for understanding the development of social functioning and its disorders. The authors used functional magnetic resonance imaging to study age-related changes in brain activity associated with ToM during childhood and early adolescence (9-16 years). Normally developed children and adolescents demonstrated significant activation in the bilateral STS, the TP adjacent to the amygdala (TP/Amy) and the MPFC. Furthermore, the authors found a positive correlation between age and the degree of activation in the dorsal part of the MPFC; in contrast, a negative correlation was found for the ventral part of the MPFC. The authors also found a positive correlation between the Z coordinate of the peak activation in the MPFC and age. The data indicated that activity in the MPFC associated with ToM shifted from the ventral to the dorsal part of the MPFC during late childhood and adolescence. No age-related changes were found in the STS and the TP/Amy regions. The authors consider that the age-related brain activity observed in the present study may be associated with the maturation of the prefrontal cortex and the associated development of cognitive functions.