Statement of Problem: Periodontitis  is  a chronic multi-factorial  infectious  disease,characterized  by  irreversible  destruction  of  collagen  fibers  and  other  matrix  constituents  of  the gingival tissues, periodontal  ligament  and resorption of the alveolar  bone  around  the  teeth  with  formation  of  periodontal  pocket. Cytokines such as IL-1β are one of the components of host’s immune system and seem to play an important role in periodontitisPurpose: The aim of this study was to determine the concentration of IL-1β as a per-inflammatory cytokine in the saliva of periodontally involved patients (generalized aggressive periodontitis and mild to moderate periodontitis) and subjects with normal periodontium.Materials and Method: In this experimental study, unstimulated saliva of 24 patients with mild to moderate chronic periodontitis, 15 patients with aggressive periodontitis, and 23 subjects with healthy periodontium was collected. The concentration of IL-1β was measured in the saliva samples by ELISA. Mann-Whitney test was used for analysis of data.Results: The results of this study showed that there was a significant difference between mean level of IL-1ß in generalized aggressive periodontitis vs. control groups and chronic mild to moderate periodontitis vs. control groups ( p <0.05).Conclusion: The findings of the present study showed that the mean concentration of IL-1ß in the saliva of periodontally involved patients was greater than that of healthy subjects and this cytokine can be agood marker for determining the status of periodontal tissues.Key words: IL-1β, Saliva, Periodontal Disease