Conformal radiotherapy has improved the technique and favored the solution of the problem of limiting cardiac and pulmonary irradiation. However new uncertainties have arisen especially with regard to treatment reproducibility. Passing from the clinical concept of CTV to the geometric concept of PTV, the anatomic identification of the different structure becomes of major importance together with the knowledge of the clinical evolution of breast cancer. The irradiation of breast lymph nodes now requires, if possible, 3D conformal processing of the treatment. Treatment parameters should be selected as to ensure adequate irradiation of target volumes while sparing healthy tissues as much as possible. In a near future, IMRT should be able to markedly improve the dose homogeneity to target with consequent lower cardiopulmonary toxicity.