Juvenile periodontitis is an inflammatory disease of the periodontium, characterized by rapid destruction of the periodontal tissues around more than one tooth in the permanent dentition. These lesions progress rapidly after onset, but tend to slow with time. The age of onset is circumpubertal, usually manifesting in a localized form around the incisors and first molars, although some generalized cases have been reported. Clinically, there is often a small amount of supragingival plaque and calculus that is not commensurate with the amount of destruction present. In addition to a unique bacterial flora, a genetic influence and an altered host response have also been demonstrated as etiologic factors. This article discusses subgingival microflora, the host response, the host-parasite interaction in juvenile periodontitis and the outcome of the treatment plan.