The aim was to assess whether or not photodynamic therapy (PDT) with adjunctive scaling-and-root-planing (SRP) is effective in the treatment of periodontitis under immunocompromised conditions. PubMed/Medline and Google-Scholar databases were searched from 1967 to May 2013 using various key words. Six studies (five experimental and one clinical) were included. In the clinical study, SRP with PDT was reported to be ineffective in treating chronic periodontitis in T2DM patients. All experimental studies reported significantly less bone loss in periodontal defects treated with SRP+PDT than those treated with SRP alone. Efficacy of PDT+SRP in the treatment of periodontal disease under immunocompromised conditions remains unclear.