The purpose of this investigation was to determine the effectiveness of irrigating periodontal pockets with povidone-iodine in reducing the incidence of bacteremia found during subgingival scaling. Twenty male patients requiring subgingival scaling had the following factors recorded on two contralateral groups of three posterior teeth: age, race, mean pocket depth, mobility, and scores of gingival, plaque, calculus, bleeding indices. In control areas, 5 ml blood samples were taken before, during and after scaling through an in dwelling Minicath. In experimental areas, the patients first rinsed with a povidone-iodine mouthwash for 1 minute, and the teeth then received a 3-minute sulcus irrigation with 10% povidone-iodine. Blood samples were taken as with the controls, and also 2 minutes after the irrigation. Blood samples were anaerobically cultured, and isolates were classified by Gram staining and cellular morphology. No significant difference in factors between control and experimental areas was noted. All preoperative blood cultures, including those taken 2 minutes after irrigation, were negative. In the 11 patients (55%0 who showed positive cultures during the scaling, cultures were positive in both control and experimental areas. None of the preoperatively recorded factors in either control or experimental ares were significantly correlated with the occurrence of bacteremia. Local degerming by mouthrinsing and sulcus irrigation with povidone-iodine prior to subgingival scaling seems neither to increase nor decrease the incidence of bacteremia.