Comparative anatomical and histologic methods have been responsible for the belief that the spheno-occipital synchondrosis in the human is an active growth center until the adult stage is reached. According to standard texts the suture closes between the eighteenth and twenty-fifth years. The present investigation was a re-examination of this question by means of midsagittal laminagraphy. The material consisted of 205 males 8 to 21 years; and 193 females 6 to 18 years. The midsagittal lamina of the spheno-occipital junction appears as a band of less radiopacity when the suture is open. Closure was found to occur first on the cranial border and to progress downward. Initial closure was found in a male of 10 years, 10 months; first complete closure at 13 years, 4 months. The last found completely open was at 15 years, 2 months. Complete obliteration was found at 8 years, 1 month in one female subject and the last completely open suture at 13 years, 9 months. In general, the closing age for the males was between 13–16 years, and the female between 11–14 years.