Normal human brains (80) varying from 22 wk gestation to 1 mo. postnatal life were graded according to convolutional development and compared with the microscopical development of kidneys and the gestational age as given by the mother. Excellent correlation was obtained between the gross appearance of the brain and the microscopical appearance of the kidney. The history of the mother mostly, but not always agreed with the anatomical appearance, which was considered a reliable guide to the gestational age of the infant.