The components of bore marrow change dramatically during lifetime. To evaluated 300 examinations of cranium and the second cervical bone in patients without known bone marrow abnormality. T1-weighted images were used to analyze the changes of lone marrow signal intensity according to the age and sex. The singal intensity of bone marrow of cranium increased most rapidly from birth to age of 10 years. Between 11 and 20 years of age, gradual increase of signal intensity was noted. There was minimal augment of signal intensigty after age of 20 years. The examination of signal intensity of bone marrow of the cranium realed slightly higher score in male than in female. The synchondrosis of the second cervical vertebra was visible in 97% These results may be useful in the detection of abnormal bone marrow signal of cranium and upper cervical spine.