This study was undertaken to evaluate patient compliance with, and acceptance of, a salt and peroxide oral hygiene regimen compared with conventional oral hygiene regimens without or with the use of phase-contrast microscope viewing of subgingival plaque over a period of 2 years. A total of 231 subjects with early to moderate periodontitis were randomly divided into four groups. All groups were repeatedly instructed and motivated in their respective regimens. Subjects also received scaling and root planing using clinical and microbial criteria. Compliance with, and acceptance of, the two oral hygiene regimens were determined at the end of the study using a structured self-administered questionnaire. Results indicated that 74% and 58% (P less than or equal to 0.01) of subjects in the conventional and salt/peroxide groups, respectively, used their assigned regimen 4 to 7 days a week during the entire study. More than half of the subjects (54%) using each of the oral hygiene regimens indicated that they flossed once daily. Inconvenience was cited by 23% of the conventional and 43% of the salt/peroxide groups (P less than or equal to 0.01) as the main reason for not using their regimens. Twenty-three per cent of conventional group and 14% of salt/peroxide group indicated that shared their oral hygiene supplies with others. Eighty per cent and 57% (P less than or equal to 0.01) of the conventional and salt/peroxide groups, respectively, stated that they liked their regimens. Ninety-six per cent of all subjects felt that their regimen helped their periodontal status.(ABSTRACT TRUNCATED AT 250 WORDS)