Background: Single photodynamic therapy (PDT) has been effective in initial periodontal therapy, but only improved bleeding on probing (BoP) in maintenance patients after a single use. Repeated PDT has not been addressed. Objectives: To study the possible added benefits of repeated adjunctive PDT to conventional treatment of residual pockets in patients enrolled in periodontal maintenance. Material and Methods: Ten maintenance patients with 70 residual pockets [probing pocket depth (PPD)X5 mm] were randomly assigned for treatment five times in 2 weeks (Days 0, 1, 2, 7, 14) with PDT (test) or non-activated laser (control) following debridement. The primary outcome variable was PPD, and the secondary variables were clinical attachment level (CAL) and BoP. These were assessed at 3, 6 and 12 months following the interventions. Results: Greater PPD reductions were observed in the test (-0.67 ᠰ.34; p=0.01) compared with the control patients (-0.04 ᠰ.33; NS) after 6 months. Significant CAL gain (+0.52 ᠰ.31; p=0.01) was noted for the test, but not in the control (-0.27 ᠰ.52; NS) patients after 6 months. BoP percentages dcreased significantly in test (97-64%, 67%, 77%), but not control patients after 3, 6 and 12 months. Conclusions: Repeated (five times) PDT adjunctive to debridement yielded improved clinical outcomes in residual pockets in maintenance patients. The effects were best documented after 6 months.