AIM: The importance of 3D conformal percutan and brachytherapy treatment planning based on CT and MRI examinations in treatment of oral cavity tumors. Introducing of the planning procedure and the selection aspects. METHOD: We present the treatment planning based on CT and MRI slices of an oral cavity tumor. The percutan or interstitial boost follow the percutan irradiation of the involved regions and lymph nodes, regarding to the target volume and the critical organs. RESULT: Our ADAC 3D planning system gives us the possibility to add the first line and the boost treatment plans, to determine and compare the dose distribution within the planned target volume and the radiation load of the critical organs. CONCLUSION: The comparative 3D radiation planning system allows higher local dose escalation required for the effective radiation treatment of oral cavity tumors with maximal protection of the surrounding healthy tissues.