Periostin, an extracellular matrix protein functioning as an important structural mediator and adhesion molecule, has been shown to be an important regulator of connective tissue integrity. This study aimed to evaluate the levels of periostin in chronic periodontitis (CP) and aggressive periodontitis (AgP) compared to non-periodontitis (NP). Individuals were submitted to gingival crevicular fluid (GCF) and saliva sampling. Periodontal examination consisted of plaque index (PI), gingival index (GI), probing depth (PD), bleeding on probing (BOP), and clinical attachment level (CAL) measurements. Assays for periostin were performed by an enzyme-linked immunosorbent assay. Periodontitis patients presented more severe clinical indices compared to the NP group (p < 0.001). The mean GCF level of periostin was lowest in the AgP group as compared to the other groups and was lower in the CP group as compared to the NP group (p < 0.001). Increased levels of periostin were observed in the saliva of patients with AgP as compared to the CP and NP groups (p < 0.05). There was a negative relationship between GCF periostin levels and clinical parameters (p < 0.01), whereas a positive correlation was observed between salivary periostin levels and full-mouth GI and CAL scores (p < 0.01). To our knowledge, this is the first report investigating periostin levels in GCF and saliva in aggressive periodontitis. The results suggest that subjects with CP and AgP exhibit a different periostin profile. Periostin in GCF may have a protective role against periodontal disease. Furthermore, salivary periostin concentrations may have a promising diagnostic potential for the aggressive forms of periodontal disease.