Antimicrobial Photodynamic therapy for the treatment of periodontitis is being increasingly gaining attention but at present, very limited data are available on the clinical and microbiological outcomes obtained following Indocyanine Green as the photosensitizer in Maintenance patients. The objective was to evaluate the efficiency of Indocyanine(ICG)-green based photodynamic therapy as an adjunct to scaling and root planing in patients enrolled in maintenance therapy. Using a split mouth study design, 24 participants enrolled in the maintenance therapy, having diagnosed as Periodontitis, were randomly subjected to scaling and root planing(SRP). The test group additionally received ICG-based (Aurogreen , Aurolabs, Madurai, India,1mg/ml) aPDT with an 810nm diode laser. Clinical assessment of Plaque index, modified Sulcus bleeding index, Probing pocket depth, Clinical loss of attachment and microbiological analysis of , and were performed at baseline and 3 months after treatment. It was observed that although there was no significant difference between the test and control group at baseline and 3 months, there was a statistically significant reduction in the mean values in both the groups at 3 months. Microbiological analysis showed substantial reduction in detection frequency of the bacteria assessed at 3 months in both the groups. Within the limits of the study, ICG-based aPDT did not show additional advantage over SRP alone at 3 months, though it could be a promising treatment modality in maintenance patients in terms of patient comfort and the treatment time taken. More randomised clinical trials should be employed to understand the exact mode of action of ICG based aPDT and its role in treatment of periodontal disease.