BackgroundThe aim of the present study was to evaluate the long-term efficacy of percutaneous tibial nerve stimulation (PTNS) for patients with faecal incontinence (FI) refractory to conservative treatment. Secondary aims were to identify predictors of response and validate new treatment pathways for partial responders.MethodsA prospective, interventional study was carried out in a specialist defecatory disorder unit from a university hospital between January 2010 and June 2017 on patients > 18 years old with FI refractory to conservative treatment. Thirty-minute PTNS sessions were performed in three phases (weekly, biweekly and monthly) up to a year, with clinical reassessment at 3, 6, 12 and 36 months.Patients were classified as optimal responders when their pretreatment Wexner score decreased > 50%; partial responders when it decreased 25–50%; and insufficient responders if it decreased < 25%. Only optimal and partial responders progressed into successive phases.ResultsBetween 2010 and 2017, 139 patients (110 women, median age 63 years [range 22–82 years]) were recruited. After the first phase, 4 patients were optimal responders, 93 were partial responders and 36 were insufficient responders. At 6 and 12 months, 66 and 89 patients respectively were optimal responders, with an optimal response rate of 64% at the end of treatment. A total of 93.3% patients with a partial response initially finally became optimal responders. Furthermore, at 36 months, 71.9% of patients were still optimal responders without supplementary treatment, although their quality of life did not improve significantly. Baseline Wexner scores ≤ 10 and symptom duration < 1 year were identified as predictive factors for positive responses to PTNS.ConclusionsPatients undergoing PTNS for 1 year following this protocol had optimal long-term responses. PTNS sessions for up to 1 year in patients who were partial responders prevents a high percentage of them from needing more invasive treatments, and maintains long-term continence in patients who were optimal responders.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10151-022-02711-z.