PURPOSE: To evaluate morphologic characteristics of the microcalcifications on mammography that were confirmed pathologically. MATERIALS AND METHODS: Forty five cases of microcalcifications on mammography (fifteen cases of benign lesion, thirty cases of maiignancy) were retrospectively reviewed. RESULTS: The number of microcalcifications within 1 cm2 were more than 5 in 22 cases (73%) of 30 malignancy and less than 5 in 11 cases (73%) of 15 benignity. The heterogeneity of microcalcifications were seen in 26 cases of malignancy (87%) and the homogeneity of microcaicifications were 11 cases of benignity (73%). The morphologic characteristics of the microcalcifications were linear-V shape in 9 cases (30%), punctate shape in 8 cases (27%), fine stippled shape in 7 cases (23%), and round dot shape in 6 cases (20%) of malignancy and, round dot shape in 11 cases (73%), punctate shape in 2 cases (13%), and linear-V shape in 2 cases (13%) of benignity. CONCLUSION: Numerous irregular microcalcifications that are heterogenous in size and morphology were strong indicators of malignancy.