The use of visible and near-infrared light to detect breast cancer has been first proposed in the 1920's. In the 1970's and 1980's, technological advances led to commercial systems for optical mammography (under the name of diaphanography) and to clinical trials. However, in the late 80's, several multi-center studies showed that diaphanography could not compete with x-ray mammography neither as a screening nor as a clinical tool. In the 90's, time- resolved optical methods, in conjunction with the use of a physical model for light propagation in breast tissue, have given new enthusiasm in optical mammography. In this talk, I will review the history of optical mammography and I will describe the results and the potential of our research approach based on frequency-domain optical mammography.