The purpose of this study was to determine the effects of professional subgingival irrigation, together with subsequent patient administered home marginal irrigation, on the incidence of bacteremia after scaling and root planing (Sc/RP). A total of 60 periodontal maintenance patients were assigned to either Group 1: subgingival irrigation, with 0.12% CHX and daily marginal irrigation with 0.04% CHX; Group 2: subgingival irrigation with 0.12% CHX and daily marginal irrigation with water; Group 3: subgingival and daily marginal irrigation with water; Group 4: Non-irrigation (control). Patients entered the study after receiving a thorough periodontal maintenance appointment including a complete examination, Sc/RP, and standard oral hygiene instruction. Blood samples were taken at the 3-month visit before and after Sc/RP. Microbiological culturing was done using the Septi-Chek system, selective and non-selective media. Results from 54 patients showed that bacteremia was detected prior to Sc/RP in 2 patients and after Sc/RP in 10 patients. No significant effect by treatment regimens on post Sc/RP bacteremia could be detected. The organisms isolated included Eubacterium lentum, Propionibacterium acnes, Streptococcus species, Neisseria species, Candida albicans, Staphylococcus species, and un-identified Gram-negative rods.