objective: the present study analyzes the consequences of x-irradiation for the development of the nervous system of rat fetuses. materials and methods: the sample included ten eight-week-old, pregnant rattus norvegicus albinus, wistar. five female rats constituted the control group and other five had their abdominal region exposed for 30 seconds to a single 0.3 gy radiation dose from a 70 kv, 10 ma gnatus odontological apparatus. at the 17th gestational day both groups were submitted to hysterectomy. selected sections were examined for comparative brain analysis of both groups. results: the clinical evaluation demonstrated no morphological difference between the control and the experimental groups. twenty-seven percent of the animals in the experimental group presented mild brain hemorrhage, while 73% of the animals had severe cerebral cortex hemorrhage and nervous tissue damage. none of the animals in the control group presented cerebral hemorrhage or nervous tissue damage. conclusion: these evidences demonstrate that low x-radiation doses may cause brain hemorrhage and, consequently, nervous tissue damage.