Background and Objective: Nitric oxide (NO) is a widespread signaling molecule which is known to influence varied biological processes. However, an uncontrolled high level of NO accelerates tissue destruction. The pathogenesis of periodontal disease is also affected by smoking which alters the inflammatory response. The present study was thus performed to assess the effect of nonsurgical periodontal treatment on salivary and serum NO levels in smokers and nonsmokers with chronic periodontitis. Materials and Methods: Forty patients with chronic periodontitis, including 20 nonsmokers and equal number of smokers participated in the present study. Probing depth, clinical attachment level, plaque index, gingival index were assessed, serum and saliva samples were obtained from the patients at baseline and after Phase I therapy at 6 weeks to estimate NO by Griess colorimetric reaction. Results: Smokers showed higher serum and saliva NO levels 30.3 ± 3.28 and 50.4 ± 4.07 μM as compared to nonsmokers 20.05 ± 2.42 μM and 37.5 ± 2.95 μM, respectively, at baseline. After Phase I therapy, both the groups exhibited significant improvement in clinical parameters and reduction in serum and saliva NO levels; however, reduction was higher in nonsmokers. Conclusion: More destructive expression of periodontal disease in smokers causes an increase in the concentrations of NO and less reduction after Phase I therapy as compared to nonsmokers with chronic periodontitis. Hence, NO levels in saliva and serum could be used as indicators of periodontal inflammatory condition.