Clinical studies suggest that gingival inflammatory response to plaque accumulation may vary between individuals. Evidence seems to indicate that there is an association between susceptibility to gingivitis and susceptibility to periodontitis. Recently, among participants in a large scale experimental gingivitis trial, we were able to identify and characterize subjects that differ significantly in their gingival inflammatory response to plaque accumulation. Research efforts are being focused on the effect of genetic, anatomic and environmental host-related factors which may be implicated in the pathogenesis of the gingival inflammatory process, and whether susceptibility to periodontitis and susceptibility to gingivitis may partly share common risk factors. In this respect, it is possible that identification of factors related to increased susceptibility to gingivitis may help identify, at an early age, subjects at risk of periodontitis. Keywords: periodontal disease/diagnosis, gingivitis, risk factors, oral hygiene