In order to gain insight into the degree to which periodontal disease is related to quality of life, research was carried out among 85 patients with moderate or severe periodontal disease in which they were asked to complete the Oral Health Impact Profile-NL49. Their scores on this questionnaire were compared with the scores of 85 control subjects of comparable age and gender. The patients with periodontal disease demonstrated significantly worse scores compared to the control group and patients with severe periodontal disease had scores which were statistically significantly worse than patients with moderate periodontal disease. The results of this study suggest a causal negative association of periodontal disease with quality of life.