The main focus of this review is polymorphonuclear neutrophilic granulocytes. Polymorphonuclear neutrophils play a pivotal role in normal host resistance to subgingival dental-plaque biofilm. Both hyper- and hypo-responsiveness of the immune system toward the microbial challenge in periodontitis have been described. We review polymorphonuclear neutrophil physiology with emphasis on the role of neutrophil functions and dysfunctions in periodontitis. Text boxes are given at the end of each subsection, which present the current knowledge on neutrophil-modulating agents as a potential therapeutic approach in periodontitis.