Background Although the first leading cause of death in China was malignant neoplasms (mortality,374.1 per 100000 person-years),the full impact of primary brain tumors (PBT) on the healthcare system is not completely described because there are a few well documented reports about the epidemiologic features of brain tumors.This study aimed to report a comprehensive assessment on the prevalence of PBT.Methods A multicenter cross-sectional study on brain tumor (MCSBT) in China was initiated in five regional centers:Daqing (northeast),Puyang (north of China),Shiyan (center of China),Ma'anshan (center of China) and Shanghai (southeast).Prevalence rate was calculated by counting the number of people living with a PBT between October 1,2005 and September 30,2006 and dividing by the total population of the five communities at January 1,2006.Estimates of prevalence were expressed as percentages and grouped according to gender and to age in fifteen-year categories.Within these strata,the rates were estimated with 95% confidence intervals (C/) using the accurate calculation of CI for Poisson distribution.A chi-square test was used to compare the various frequencies with α＜0.05.Age-standardized prevalence with the direct method was calculated with the ten-year age-specific prevalence and the age distribution of the Chinese population in 2010,obtained from Worldpopulation prospects:the 2008 revision.Results We estimated that the overall prevalence of PBT was 24.56 per 100 000 (95% CI,14.85 to 34.27),and the overall prevalence of PBT in female population (30.57 per 100 000 and its 95% CI ranged from 19.73 to 41.41 ) was higher than that in male population (18.84 per 100 000 and its 95% CI ranged from 10.33 to 27.35).However,the discrepancy between genders was not statistically significant because the 95% CI overlapped.Of 272 cases of newly diagnosed PBT,the proportion of histological subtypes by age groups,gender was statistically different (χ2=52.6510,P <0.0001).More than half of all reported tumors (52.57%) were either gliomas or meningiomas.For the youngest (aged from 0-19)strata of the population,glioma appeared to occur more than other subtypes,accounting for 55.56% of all of cases.The majority of brain tumors presented in those aged from 20 to 59 years was pituitary adenomas (45.12%) and gliomas (31.10%).Opposed to brain tumors in adults and teenage,gliomas only accounted for 22.22%.Meanwhile,the median ages at diagnosis of the patients with PBT were similar between males and females except for pituitary adenomas (male: 59 years old; female: 45 years old).Conclusions Age standardized prevalence of PBT is 22.52 per 100 000 (95% CI,13.22 to 31.82) for all populations,17.64 per 100 000 (95% CI,9.41 to 25.87)for men,and 27.94 par 100 000 (95% CI,17.58 to 38.30)for women.Age standardization to China's 2010 population yielded an estimated population of 304 954 cases with PBT.Our prevalence estimates provide a conservative basis on which to plan health care services and to develop programmatic strategies for surviving.In the future,it would be helpful to have long-term observed survival rates that would make the assumptions and the resulting imprecision in the current estimates unnecessary.