Calcium phosphate is deposited in many diseases, but the molecular basis of mineralization remains largely unknown. Biomineralizied calcifications that are formed by calcium deposits are also detected in breast mammograms. Some of the detected microcalcifications are thought to be related with malignancy. Taken together, calcifying nanoparticles (CNP) may be thought as a source of malign calcifications in breast cancers. The aim of the study is to research the presence of CNP in breast tumor tissue. With this aim, the presence of CNP was investigated by culturing 16 patients' breast tumor tissue and from 2 pathologic tissues with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Their growth was monitored by optical density (OD) at a wavelength of 650 nm. CNP couldn't be found in the analysed tissues. The presence of CNP in the breast tumor tissue was researched for the first time. We could not find CNP in the breast tumor tissue, but we think this research will open a new field of study for researchers.