Ovarian cancer is one of the common malignant tumors in female reproductive organs. Psammoma bodies occurring in cell population is considered to be a phenomenon of ovarian serous carcer. In this paper, psammoma bodies from ovarian serous carcinomas were investigated by using SEM, EDAX, XRD, FTIR and HRTEM. The results show that the mineralized matter of the psammoma bodies with the concentric lamellated structure is composed of nano_size whewellite and carbonate hydroxylapatite. The former is deposited in the inner part of the psammoma body in a relatively high crystallinity, whereas the latter in the outer part in a low crystallinity.