A total of 442 cases (adult male 256 cases,adult female 142 cases and young specimens of both sexes 44 cases) of suprameatal spines of 225 chinese crania,217 bilaterally and 8 unilaterally,were investigated.They are divided into 4 types according to the degree of development in a decreasing order as 1.markedly developed,2.well developed,3.slightly developed and 4.undeveloped. The percentage of markedly developed and well developed types is much higher in male adults (17.9% and 41.80% respectively) than in the female adults (5.63% and 20.42% respectively),while the percentage of slightly developed and undeveloped types is reversely much higher in female adults (61.97% and 11.97% respectively) than in male adults (35.94% and 4.30% respectively). In young cadavers of both sexes 52.27% of the cases are not developed,40.91% slightly developed,only 6.82% well developed and none markedly developed. The results obtained show statistically the existence of age and sexual differences in the development of the suprameatal spines.They are better developed in male adults than in female adults and in adults than in non-adults. The suprameatal spine is an important bony land mark for operations upon the tympanic antrum of the midde ear,so its exact state of development and location be becomes prime importance for the surgeons.