While mammography has become a routine method both for the screening and preoperative assessment of breast disease, the role of this modality, especially when compared with newer techniques of breast imaging, needs continued assessment. Recent advances using sonographic principles and diaphanography (light transillumination) must be compared with mammography to define specificity, sensitivity, and accuracy in assessing breast lesions. During a 16-month period between November 1982 and February 1984, 467 women with clinically apparent breast disease (symptoms or palpable lesions) were each studied using all three imaging techniques of mammography, sonomammography, and diaphanography. Of 168 women recommended for biopsy on the basis of these techniques, 84 women had histologic confirmation during this study period. Benign breast disease was diagnosed histologically in 38 women, while carcinoma was found in 46 patients. These techniques showed no significant differences in predicting benign or malignant disease when rates of sensitivity, accuracy, and specificity are computed. Diaphanography (lightscanning), allowed for consistently correct interpretation of cases proven to be histologically malignant and showed a false-negative rate comparable with x-ray mammography. We conclude that diaphanography is a sensitive indicator of both benign and malignant breast disease while serving as a reliable predictor of clinically apparent breast lesions without the potential problems of radiation exposure.