The main aim of this study was to assess the efficacy of percutaneous posterior tibial nerve electrostimulation (P-PTNS) in urge urinary incontinence (UUI) and faecal incontinence (FI) refractory to first-line treatment. A secondary aim was to identify predictors of treatment response. To do this, we performed a 2-year analytical, longitudinal and prospective study in patients with UUI and FI treated with P-PTNS. We included patients with UUI and FI who were treated with P-PTNS and who completed the bladder/faecal incontinence diary and severity and quality of life questionnaires. We excluded patients with neurogenic UUI and those who abandoned treatment or did not complete the questionnaires. We assessed demographic and clinical variables (micturition/defecation habits pre- and postreatment), severity scales before and after treatment (ICIQ-SF, Sandvick and Wexner), subjective improvement and quality of life (IQOL and FIQL pre- and postreatment). The statistical analysis was conducted using SPSS v19. The sample consisted of 21 patients divided into 2 groups: -UUI group, 9 patients. After P-PTNS, there was a statistically significant improvement in diurnal (p=.018) and nocturnal (p=.016) urinary frequency, urgencies/day (p=.018), urine leakage/day (p=.027), ICIQ-SF and Sandvick (p=.018), and IQOL (p=.012). This improvement was related to exercise (p=.039) and prolapse (p=.05). -Group FI, 12 patients. After P-PTNS, there was a statistically significant improvement in defecation frequency (p=.027), incontinence (p=.012), Wexner scale (p=.007), and FIQL in its 4 dimensions (lifestyle, behaviour, embarrassment p=.005; and depression p=.008). This improvement was related to age (p=.048), time since onset (p=.044) and prolapse (p=.026). The P-PTNS is effective in UUI and FI refractory to conventional treatment. Treatment response is affected by several factors.