Medico-legal data are presented on 995 child deaths, 361 girls and 634 boys aged 0–18 years, whose brains were weighed at the time of autopsy using a standardized weighing technique (the brains were weighed before fixation, immediately after entire removal; the medulla oblongata was divided in the foramen magnum). From the results it appears that the brain weights are greater than those reported in a previously published series. This may be ascribed to a higher degree of oedema and a shorter duration of illness, or an absence of illness; another explanation may be related to a difference in origin. It should be remembered that post-mortem brain weights exceed the ante-mortem weights by up to 9%. The greater part of brain growth is completed by the end of the 2nd year of life, and thereafter the brain weight in girls is on the average a little lower than that in boys. No significant differences in brain weights are found in the various groups of causes of death; the brain weights in the group of sudden, unexpected infant deaths especially do not deviate from those in the other group