Increasing evidence suggests that maternal periodontal disease is associated with gestational outcomes, including low birth weight and preeclampsia. One of the major periodontal pathogen, Porphyromonas gingivalis, is a Gram-negative anaerobe that can invade and survive within epithelial cells, disrupts cytokine expression and increases cell proliferation while suppressing apoptosis. All of these properties could potentially disrupt homeostasis in the placental tissues. It is also potentially important that,during the first 10-12 weeks of gestation, the placenta is in a state of physiological hypoxia, which would facilitate growth of anaerobes such as P. gingivalis. Although several authors have isolated P. gingivalis from the placenta of pregnant women with preeclampsia, little is known about the ability of this bacterium to infect and survive in trophoblasts. The objective of this study is to evaluate in vitro the invasiveness and survival of P. gingivalis in human trophoblastic cultures of the first and third trimester of gestation.