Objective: The aim of the present short-term randomized clinical trial was to assess the efficacy of scaling and root planing (SRP) with and without adjunct antimicrobial photodynamic therapy (aPDT) in the treatment of chronic periodontitis (CP) among cigarette-smokers and never-smokers. Materials and methods: Demographic information was collected using a questionnaire. Cigarette-smokers (group-1) and never-smokers (group-2) with CP were included. Treatment wise, these individuals were divided into two subgroups as follows: (a) SRP alone and (b) SRP with adjunct aPDT. Periodontal parameters (plaque index [PI], bleeding on probing [BOP], clinical attachment loss [AL] and probing pocket depth≥4 mm [PD] were measured at baseline and at 1 month and 3 months’ follow-up. Group comparisons were done using the Kruskall-Wallis test. Results: Eighty-three male patients with CP (Group-1: 42 cigarette-smokers and; Group-2: 41 never-smokers) were included. In group-1, individuals that received SRP alone and SRP with adjunct aPDT had a mean history of cigarette smoking of 11.7 ± 0.3 and 12.5 ± 0.4 pack years. At baseline, PI, BOP, PD and clinical AL were comparable among all individuals in groups 1 and 2. At 1 month and 3 months’ follow-up, PI (P < 0.05), PD (P < 0.05) and clinical AL (P < 0.05) were higher among all individuals in group-1 compared with group-2. In Group-2, PI, BOP, PD and clinical AL were comparable among all individuals at 1 month and 3 months’ follow-up. Conclusion: Outcomes of SRP with or without aPDT for the treatment of CP are compromised in cigarette-smokers. Among never-smokers with CP, outcomes of SRP with or without aPDT are comparable. The significance of aPDT in this regard remains questionable.