The aim of this study was to evaluate retrospectively the stability of treatment outcomes of adult anterior open bite (AOpB) cases, treated non-surgically, using a conservative approach with lingual orthodontics (LO). Thirty-nine adult AOpB patients consecutively treated by one operator (SG), with Ormco™ Generation 7 LO brackets and a conservative treatment protocol, with or without extractions, were evaluated clinically before treatment, at the end of active orthodontic treatment, and after a follow-up period, divided into a short-term group (ST): 1-2 years post-treatment, and a long-term group (LT): more than 2 years and up to 11 years post-treatment. All patients had a positive overbite at the end of active treatment (T2). Stability of the open bite correction was seen in 87.2 per cent of the patients (T3). Relapse to a negative overbite was seen in one patient (2.5 per cent). Post-treatment improvement of the overbite was demonstrated, with no difference between the ST and the LT groups. Stability of the transverse molar relations was significantly correlated with stability of AOpB correction. The LO appliance with the presented treatment protocol is a viable procedure for AOpB correction in adult patients, who are not suitable for surgical procedures, to improve or to enhance facial aesthetics. Post-treatment improvement of the overbite was observed in patients treated with this treatment approach in this study.