Aim—To identify predictors of compliance during non-surgical and supportive periodontal therapy (SPT). Materials and Methods—In this retrospective study, demographic, dental, medical data of 427 new patients in a private practice were collected. Data were analysed in statistical models with non-surgical therapy and SPT compliance used as dependent variables. Results—Of the 427 patients, 17.3 % never agreed to initial therapy, 10.7 % never completed therapy and 20.8 % completed treatment, but never entered SPT. Of the 218 SPT patients, 56% became non-attenders after a period of 20 months, 33 % were erratic attenders and 10.5 % were regular attenders until the end of the observation period (5.5–6.5 years). Patients became erratic attenders af...