The EEG of an 11-year-old hypopituitary dwarf was investigated to determine whether the disorder was accompanied by a disturbance in cortical maturation. By means of a previously derived equation relating age and the first four central moments of the EEG interval histogram in normal children, the dwarf's developmental age was estimated from his EEG to be only about 6 1/2 years. After 8 years of treatment with human growth hormone, age estimated from the EEG was 8 2/3 years - an increase of barely more than 2 years.