Screening mammography contributes to the improvement of breast carcinoma survival through early detection and treatment of non-palpable lesions. Microcalcifications are of fundamental importance in this process. The percentage of malignant lesions found in biopsies for microcalcifications varies from 10% to 40%. The purpose of this study was to evaluate the relationship between clinical and radiologic records and the presence of malignant breast diseases. To establish the basis for the study, 211 mammographic files showing clustered microcalcifications from 204 women were prospectively reviewed and clinical records were retrospectively drawn. Definitive pathologic analysis was available for all. The value for cancer of each criterion was investigated by univariate and multivariate analyses. A first analysis was performed on the entire population and a second one was performed with stratification on morphologic subgroups. There were 99 malignant lesions (47%). In the entire group, no clinical criterion was significant. In the univariate analysis, five radiologic variables were significant: morphologic type(p < 0.0001), number of calcifications per cluster(p < 0.0001), linear or triangular distribution(p < 0.0002), diameter of the area (p < 0.01),and number of clusters (p = 0.011). In the multivariate analysis, two criteria remained significant: morphologic type 4 (irregularly punctiform) or 5 (vermicular) microcalcifications(Le Gal's classification) (p < 0.0001) and diameter of the cluster larger than 25 mm (p = 0.032). In subgroups,in the multivariate analysis, the "age > 60 years" criterion was statistically significant in the group of regular punctiform microcalcifications (type 2); for irregularly punctiform microcalcifications (type 4), "number of microcalcifications > 20" was significant. The morphologic features of microcalcifications must be the first criterion evaluated. They permit identification of characteristically benign (annular calcifications) or malignant calcifications (vermicular calcifications). For the remainder of the calcification types, other criteria must be taken into account, and their value vary with (according to) the morphologic aspect. These findings have implications for the management of women with microcalcifications and could help breast specialists make treatment decisions.