Abstract. The objective of this study is to verify the effects of 0.1% povidone-iodine (PVP-I) as subgingival irrigation on chronic periodontitis patients after 4, 6 and 8-week treatment. A clinical trial was conducted on 18 patients from 30 to 65 years old (mean age: 51.1±11.2) with moderate or severe chronic periodontitis at Faculty of Odonto-Stomatology at University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam 2017. Treatments of chronic periodontitis included oral hygiene instruction, scaling and root planing plus 0.1% PVP-I irrigation. Clinical parameters including plaque index (PI), gingival index (GI), bleeding on probing (BOP), pocket depth (PD), clinical attachment loss (CAL) and the bacteria level in subgingival plaque (BANA test) were evaluated at 4-time points: T0 (the initial visit), T4 (4 weeks after the initial visit), T6 (6 weeks after the initial visit) and T8 (8 weeks after the initial visit). The whole mouth (PI, GI, BOP, PD and CAL) parameters and BANA test score showed statistically significant reductions from T0 to T8 (p<0.001). The PD and CAL of moderately deep (PD ≥5mm and <7mm); and deep pockets (PD ≥ 7mm) were significantly decreased from T0 to T8 (p<0.001). The findings from the present study demonstrated that the topical application of 0.1% PVP-I, used as subgingival irrigation along with subgingival root debridement had beneficial influences on chronic periodontitis treatments.