Objective: To determine if HIFU is secure and effective for the treatment of intracranial neoplasm by observing pathological regression at the focus in normal New Zealand Rabbits’ brain tissue after ablation.Methods: We selected suitable doses of exposure to ab-late 12 rabbits’ brain tissue

and sacrificed them successively at 1

3

7

14

28 and 60 days(d) after sonication

observing target lesions grossly and microscopically to identify the biological characteristic and pathologic changes.The ultra-structural changes were also observed immediately after sonication.Results: We took the 5s and 10s for each exposure time in the studies.Different ranges of lesions were pro-duced after different exposure time

especially on 28d

although grossly and microscopically the lesion were almost the same in early period.Finally the 10s sonicated area regressed to scar of glia

but no apparent lesion was found in the 5s area.Ultra-structural examination showed the integrity of cell and vascular structure were destructed in 10s area

but remained intact in 5s area.Conclusion: HIFU could ab-late deep localized brain tissue with little effect on the superficial brain tissue.The restoring mode of sonicated lesion is correlated with ex-posed doses

and it is reversible when using suitable dose of exposure.In conclusion

it is secure and effective to use suitable dose of HIFU in the treatment of intracranial neoplasm and some experimental data are provided for future clinical investigation.