The pattern of primary brain tumors have not been reported in Iran and the etiology remains largely unknown. The need for current estimation of geographical and secular variation is clear. The purpose of this study was to review cases of brain tumors treated in Shariatti hospital, a neurosurgical center, over the twenty five years from 1978 to 2003. A descriptive, retrospective study was made of 3,437 cases who were hospitalized with brain tumors. Data abstracted from the patients' clinical records included age at the time of admission , sex, histological diagnosis and tumor location. The frequency distribution of brain tumors by age and sex, and histology was calculated for comparison with the literature. There is a preponderance of males over females, the overall ratio of male/female cases was 55.4% to 44.6% (P< 0.05). The average age of the patients at the diagnosis was 33.9 years (SD = 18.1) with a median of 34 years and a ranged from 1 to 95 years. The mean age did not significantly differ between the genders. Of recorded series cases, 20.1% brain tumors occurred in children 15 years and younger, with a mean + sd of 8.7 + 3.9 years, and 79.9 % of cases in adults with the mean + sd of 40.2 + 14.4. The five most common histological types in both sexes were meningioma in 892 cases (26%) followed by astrocytoma in 805 cases (23.4%), pituitary adenoma in 488 cases (14.2%), glioblasomaoma in 278 cases (5.1%) and ependymoma in 166 cases (4.8%). These accounted for 84 % of all brain tumors. The 10 most frequent brain tumors were ranked separately by sex and age groups. Male predominance was observed for the astrocytoma group, craniopharyngiomas, ependymomas, glioblastomas, medulloblastomas, and pituitary adenomas. Meningiomas were the only tumors with a significant excess in females (p<0.05)-- some 28% of cases occurred in patients younger than 20 years of age; 45% cases 21- 45 years of age; 25% cases 46-65 years of age, and 2% cases in patients older than 65 years of age. In conclusion, the results present an important epidemiological basis for understanding of the brain tumor burden in Iran. Wider epidemiological studies of a prospective nature are now required .