Background and Purpose: Antimicrobial photodynamic therapy using Methylene blue (MB-PDT) has been proposed as an adjunctive to scaling and root planing (SRP) to provide preferable results for the treatment of periodontitis. The multi-factor mechanism of aPDT action correlates with various influencing components such as the photosensitizer and the light delivery system. The paper aims to review the recorded parameters of MB-PDT from clinical trials of periodontitis which may serve to improve the treatment of periodontal diseases. Materials and Methods: PubMed search engine was used to identify human clinical trials of PDT in dentistry. After applying specific keywords, additional filters, exclusion criteria, the initial number of 17378 was reduced to 12. Results: More than half of the articles of SRP + MB-PDT presented better results [pocket depth (PD) reduction, clinical attachment level (CAL) gain, etc.] compared to SRP alone in the treatment of periodontitis. Conclusions: While more clinical evidence is needed, recent studies demonstrate that MB-PDT combined with SRP show a greater potential as a treatment of periodontal diseases in comparison to SRP alone.