The authors report on a consecutive series of 305 women under age 30 undergoing mammography because of a solid palpable mass. The presence of diffuse parenchymal density impairing radiologic interpretation was observed in 71% of cases. Cancer was not demonstrated at mammography in 5 of 18 cases. Radiologic suspicion did not improve the cumulative sensitivity for cancer and did not influence clinical management in cancer cases. Mammographic contribution in reducing unnecessary biopsies of benign lesions was also poor and parallelled that of aspiration cytology. Mammography is not recommended in the differential diagnosis of palpable masses in women under 30 and should be limited to the preoperative assessment of cases with a strong suspicion of cancer.