Urge urinary incontinence (UUI) is a chronic debilitant condition that characterizes some overactive bladder (OAB) patients in absence of any urinary tract infection (UTI). In our center we use intradetrusor injection of ‘Onabotulinum toxin A' as second step after medical therapy failure. The objective of this study is to verify the improvement in the patients' quality of life (QoL) and also to evaluate the effective dose over time. We observed 62 patients between March 2019 and March 2021 (38 females and 24 males), previously treated with oral drugs (antimuscarinic and/or beta-3 adrenergic), 14 of these had pathologies - 8 of them neurological. These last patients were injected by 200 U, all the others (52) by 100 U - Botox®; Allergan, Irvine, CA, USA. Follow-up included monitoring of the following parameters at 3, 6, 12, 24 months: urinary leaks (PAD test), Clean Intermittent Catheterization (CIC), OAB questionnaires, side effects. The mean age was 62.5 years. 3 patients (5%) had early adverse effects after injection (1 vomiting, 2 pelvic pain), 5 (8.3%) needed CIC at 3 months, 1 of them also at 6 months (they were among the 8 neurological patients who underwent 200 U dose). 56 (93.3%) answered positively to the questionnaire. Botox® treatment showed a reduction in urinary leakage at 3 and 6 months and a significant lowering of Pdet at 6 months (p<0.05). The side effects at 3 months were 1 haematuria and 3 UTI - 1 also recurred at 6 and 12 months. Botox® is a valid therapeutic option for OAB patients. 100 U appears as an effective dose, however after 12 months it seems to lose its effect. There were no clinical relevant differences between 100 and 200 U doses. Engineered modified or liposomal botulinum toxins could represent novel more effective therapies over time.