Purpose: The aim of the present qualitative study was to analyse patients' attitudes towards oral health and experiences of periodontal treatment. Materials and Methods: Patients who were referred to a specialist clinic in periodontics were subjected to open-ended interviews before (Abrahamsson et al, 2008), as well as after, the phase of cause-related periodontal therapy. An interview guide was used with themes of interest. The time interval between the interviews was about 6 months. Because the study focused on psychosocial interactions, the qualitative method used for the analysis was Grounded Theory (Glaser and Strauss, 1967). Data collection and analysis were simultaneous processes that focus on psychosocial processes, existing problems and how these problems were dealt with. The interviews were tape-recorded and transcribed verbatim, and consequently analysed in a hierarchical coding process until saturation was met (n = 16). Results: In the analysis, a core category was identified: 'Understanding the seriousness of the disease condition'. This core concept was related to four additional categories and dimensions: 'The need to be treated respectfully', 'To gain insight', 'Frustration about the financial cost for treatment' and 'Feelings of control over the situation'. Taken together, the core category and its related subcategories described a psychosocial process that was related to periodontal treatment. Conclusions: The results elucidated the patients' vulnerability and the importance of patient communication in the treatment for chronic periodontitis in order for the patient to feel in control of the situation. Keywords: chronic periodontitis, grounded theory, interviews, oral health