Porphyromonas gingivalis is a Gram-negative oral anaerobe highly involved in the pathogenesis of periodontitis, an inflammatory disease that destroys the tooth supporting tissues, eventually leading to tooth loss. P. gingivalis has the capacity invade locally periodontal tissues and evade the host defence mechanisms. In doing so, it utilizes a panel of virulence factors that cause deregulation of the innate immne and inflammatory responses. The present review discusses the invasive and evasive strategies of P. gingivalis and the role of its major virulence factors in these, namely lipopolysaccharide, gingipains and fimbriae. Moreover, the role of P. gingivalis is highlighted as a “keystone” biofilm species in orchestrating a host response.