Although routine patient education concerning periodontal disease is recommended as a means of improving oral health, strong associations between oral health knowledge and plaque or gingival inflammation scores have not been demonstrated. This study examined associations between four knowledge scales (likelihood of keeping teeth, signs of disease, role of diet, role of oral hygiene measures) and six periodontal status measures (plaque, gingivitis, calculus, probing depth, attachment loss, missing teeth) among 1088 regularly attending dental patients. In bivariate correlation analyses, there was a weak, direct association between stronger expectations of keeping teeth and better levels of periodontal health, while an inverse association between knowledge of signs of periodontal disease and better periodontal health was noted. Level of knowledge of the role of oral hygiene or of diet in periodontal disease was not associated with level of disease. When effects associated with age, sex, race, and different dental practices were held constant, these patient knowledge scales did not explain substantial proportions of variance in the periodontal disease measures. Among regular utilizers, the effects of receipt of dental care may be more determinative than level of patient knowledge.