Electron beam radiation therapy is the mainstay of treatment for skin cancers of the head and neck. It is important to carefully map out the extent of the lesion on the patient and add at least 1-cm margin. A larger margin up to 1.5 to 2.0 cm can be used if this does not encroach upon vital structures or if there is uncertainty about the edge of the lesion. Our practice is to place wires around the final margins, which correspond to the electron field edge. We also construct custom wax bolus of 0.5 to 1.0 cm to fit perfectly over the involved skin, to provide optimal dose distribution. This approach will satisfactorily deal with the majority of early or intermediate-sized lesions. Figures 23-32 and 23-33 show a clinical example.