Objectives The purpose of this prospective study was to investigate the effect of nonsurgical periodontal treatment (PT) on anxiety/depression scale scores and on gingival crevicular fluid (GCF) cortisol (COR) and dehydroepiandrosterone (DHEA) levels. Methods Fifty-five participants with generalized chronic periodontitis (GCP group, n: 21), with localized chronic periodontitis (LCP group, n: 19) and with gingivitis or healthy (control group, n: 15) subjects were treated and followed up for 6 months. Clinical periodontal parameters include plaque index, gingival index, bleeding on probing, probing depth and attachment level; psychosocial measurements include Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI 1-2) psychometric instruments; hormone levels in GCF including COR and DHEA were evaluated. Results All clinical parameters were significantly decreased (except attachment loss) after PT (p < 0.05). No significant differences were observed between the two groups for STAI-1-2 and BDI scores, either at baseline or at 6 months (p > 0.05). COR levels were statistically lower following PT in GCP and LCP groups when compared to the baseline levels (p < 0.05). DHEA values at baseline and 6 months did not show significant differences. Conclusion Within the limits of the study, decreased GCF COR and unchanged GCF DHEA levels were determined in nonsurgically treated patients regardless of the extent and severity of periodontitis.