To evaluate the development of the sphenooccipital sychondrosis as seen on high-resolution thin-section CT scans. We retrospectively reviewed the records of 253 patients, ages 1 to 77 years old, who had had thin-section CT examination of the skull base. An ossification center appeared midline in the patients who were 8 to 13 years old. Six of 12 girls showed additional symmetric ossification centers on either side of the midline; however, this pattern was not seen in boys. No sphenooccipital synchondrosis persisted in any patient past the age of 13 years. High-resolution CT scans of the skull base can show a pattern of progressive ossification of the sphenooccipital synchondrosis, which can be readily recognized and predicted.