The first Symposium on ~iammary Pathology organized by the International Society against Breast Cancer was held in Paris on December 3-7, 1979. The programme was divided into sections with morning lectures on current topics in mammary pathology given by invited speakers, followed by discussions, and, in the afternoon, emphasis on practical work, such as slide seminars, technical explanations of tissue and cell preparations for histology, cytology, electron microscopy and tissue culture work. The morning sessions were held at the Racing Club of France, 5 rue Eble, 75007 Paris and the organizers of the meeting wish to thank the RCF andits President, Mr. R. Menard for their kindness and generous help in the arrangement of the symposium. The afternoon workshops too~ place at the Institut de Pathologie et de Cytologie Appliquee {Director Professor J. de Brux) , rue des BeIles Feuilles, Paris XVI, with the help of staff members from this Institute. The editors of the Proceedings of the Symposium wish to thank the contributors for their help in providing manuscripts for publication and for complying with the instructions given by the editors and the Plenum p;ubli- shing Company. Financial supports providea by the Ligue Nationale Fran9aise contre le Cancer and the FEGEFLUC are gratefully acknowledged. It is hoped that the present volume will provide stimuli for future work on clinical and basic research in mammary pathology.