Trophoblast cells contribute in all the stages of pregnancy starting from implantation of the embryo to parturition through their unique inherent properties of invasion, proliferation, differentiation and endocrine secretions. Hence, successful outcome of pregnancy depends greatly on the coordinated functioning of the trophoblast cells which is brouth about largely by the timely expression of integrins, adhesion molecules, cytokines, hormones and generation of nitric oxide. Loss of this coordination leads to adverse consequences like early pregnancy failures, preeclampsia, molar pregnancy and choriocarcinoma. In order to have better understanding of normal physiology of pregnancy and to assess the nature and causes of these pathological situations, in depth study of trophoblast function has been carried out by us and several other investigators.