The changes in the SN line inclination during the growth esere studied in relation to time of observation. The superimposition of two age-different cephalometric headfilms on stable strnctures of the cranial base was performed. The extent of changes according the period of observation was investigated. The mean rotation of SN line 0.45° was in the group of patients with the period of observation less than 2 years, whereas in the group of patients with the period of observation more than 2 years the mean rotation of SN line was 1.60°. In the course of the facial growth, the ventrocaudal shift of the N point, even remodeling of sella turcica and dorsocranial shift of S point, in longer time-interval may occur.

        Key words: SN line - X-ray headfilms - superimposition