The developmental status of 60 galactosemic infants, their subsequent intellectual level, school status, visual-perceptual skills, and EEG results were analyzed. In addition, the intelligence of the parents and the unaffected siblings, as well as the educational and vocational status of the parents, were also investigated. The results reveal that the highest level of mental development was in the preschool age group. The lowest level, and still within normal limits, was in the school-age children. The overall findings are consistent with earlier observations that better progress is found in those individuals whose dietary control is instituted at the youngest age level.