After having briefly described the technique of diaphanoscopic examination of the breast, the Authors illustrate the normal and pathological findings. Since the diaphanoscopic images can only give a rough, inadequate and not often pathognomonic idea of the symptomatology of a given condition, the pathological symptomato-gy is recorded by illustrating the diaphanoscopic pictures of various mammary conditions. The Authors recognize to mammary diaphanoscopy a role of complementary test in studying breast diseases, since the information provided by this technique need to be integrated with the clinical findings and possibly with the mammography report.