MR Imaging was performed on 10 healthy volunteers and 86 patients, using a 0.5 T superconducting magnet and a dedicated coil to image both breasts simultaneously. The patients were selected by the presence of nodules at clinical examination. Final diagnoses were made either at histology--in the patients who underwent surgery--or at cytology, with fine needle biopsy. The MR findings of the different breast diseases are discussed. In spite of an improved spatial resolution and of a very good natural contrast between different tissues, MR Imaging does not allow a satisfactory characterization of the lesions; its use is thus limited to the staging of cancers which need a better therapeutic planning.