OBJECTIVE: To evaluate the long-term results of traditional therapy consisting of initial preparation followed by mucogingival surgery including bone recontouring and regular maintenance treatments. DESIGN: 125 patients between 25 and 70 with a generalised periodontitis of the type adult and rapidly progressing periodontitis were selected. These patients were treated according to a fixed protocol by a periodontist and a dental hygienist. SETTING: The Practice for Periodontology in Groningen. METHODS: Patients were treated in a practice limited to periodontology. Before and 5 years after treatment the following data were assessed: plaque- and bleeding-score, probing pocket-depth, mobility and furcation involvement. Furthermore the reason for extraction was established. RESULTS: In general a great reduction in plaque- and bleeding-score and probing pocket-depth was much better in case of good oral hygiene. Within 5 years after treatment only 1.1% of the teeth were extracted. Furcations with through and through involvement in combination with deep residual pockets were mostly the reason for this. CONCLUSION: It is concluded that with traditional periodontal therapy following a strict protocol including regular maintenance treatments excellent treatment results can be achieved.