There have been few studies of the radiographic findings of breast cancer in young women. We report our series of 42 cancers in 39 women under the age of 35 who had a mammogram prior to biopsy. Abnormal findings were present on 86% of the mammograms with 94% of the abnormalities classified as high or intermediate suspicion. Mammographic findings were: mass in 50%, calcifications in 31%, diffuse inflammatory changes in 11%, and an asymmetric density in 8%. Six of the mammograms were normal. While young women are usually expected to have dense breasts, 23 mammograms showed either entirely fatty or mixed fatty/glandular tissue. Dense parenchyma infrequently obscured a palpable malignancy. We conclude that mammography can provide important diagnostic information in young women with breast cancer.