Stereotactic Body Radiation Therapy (SBRT) is a new treatment regimen that uses less (< 5) fractionations and a higher fractional dose to treat certain tumors and achieve similar or even better treatment outcome as the conventional fractionation scheme. With a similar outcome, the shortened treatment course of SBRT is very convenient to patients. However, a high fractional dose is more likely to cause complications to normal tissues. Better treatment plan and more precise patient setup and more accurate treatment delivery are therefore needed to minimize the irradiation of normal tissue. The SBRT plan is made with all possible measures, even at the expense of longer treatment time and complex setup scheme, so as to have high conformality of prescription dose to the lesion(s) and low dose to normal critical organs. Novel imaging modalities like CT or cone-beam CT are installed in the treatment room to acquire pre-treatment volumetric images which are compared with simulation CT images for more precise setup. Finally, high-precision multi-leaf collimators are used to shape and modulate the beam so that pencil-thin radiation beam can be accurately delivered to the tumor while avoiding surrounding normal tissues. The combination of better planning, setup and delivery has reduced the uncertainties of radiotherapy to an unprecedented level and keep the normal tissue complication rate of SBRT similar to that of conventional radiotherapy.