The submitted investigation describes long-term changes of 3 main cephalic dimensions (head circumference, maximal length and maximal width of the head) and analyses the possible influence of positioning of infants after birth (prone, supine and side sleeping position) on these changes. Information about children aged 6 months to 3.99 years, where the need of up-to-date data is greatest, were collected as part of an extensive anthropological survey implemented in 1995 to 1997 in the entire Czech Republic. The authors confirmed the trend of debrachycephalization, which is manifested by a statistically significant increase of the maximal length of the head and a statistically significant decrease of the maximal width of the head, as compared with children examined in the anthropological survey in 1956 to 1962 (1). These changes were established in the group of boys (200 boys) as well as in the group of girls (167 girls). The differences of the magnitude of long-term changes between boys and girls were not significant. Evaluation of the long-term changes of the head circumference in the entire group of 366 children aged 0.5-3.99 years (the head circumference of one girl was not measured) revealed a statistically significant increase of this dimension. During the period from 1956/62 till 1996, the influence of positioning on the magnitude of long-term changes of head circumference was not proved. We can say the same about the maximal length of the head of boys and girls and about the maximal width of the head of girls. Only between three differently positioned groups of boys (prone, side, supine) statistically significant differences in the magnitude of long-term changes of the maximal width of the head were found (p < 0.05). Highly significant changes of the maximum width and maximum length of the head occurred as compared with a reference group in all three groups of positioning of infants and in both sexes. The trend of debrachycephalization seems to be thus a more potent factor, which affects long-term changes in the shape of the head, then the predominating sleeping position during the first months after birth. This conclusion is supported by the persisting trend of debrachycephalization, although the supine position is now preferred.