To assess the impact of asymptomatic bacteriuria (ASB) on the safety and efficacy of intradetrusor onabotulinumtoxinA injections in patients with overactive bladder and neurogenic detrusor overactivity. We reviewed the medical records of patients who had received onabotulinumtoxinA between 2009 and 2014. Safety analysis was based on the appearance of urinary tract infections (UTIs), hematuria, and need for hospitalization because of related adverse event(s) in the month after injection. Patients who underwent urodynamic study before and 3 months after the first onabotulinumtoxinA treatment were included in efficacy analysis. Changes in maximal cystometric capacity (MCC), bladder compliance (BC), maximal detrusor pressure at maximal involuntary detrusor contraction (Pdetmax), and detrusor leak point pressure (DLPP) were assessed. Totally, 183 patients underwent 457 injection sessions. ASB was found in 38.8% (185) of urine cultures taken before injections. After treatment, 49 patients (with or without ASB) developed UTI. Urosepsis did not occur. The odds ratio of UTI in patients with ASB was 16.48. The efficacy cohort, consisting of 83 patients, showed that ASB had no significant effect on any of the efficacy parameters (MCC-risk ratio [RR]: 0.93, 95% confidence interval [CI]: 0.72-1.21; BC-RR: 0.88, 95% CI: 0.62-1.24; Pdetmax-RR: 0.9, 95% CI: 0.69-1.21; DLPP-RR: 1.69, 95% CI: 0.72-3.97). ASB is common among patients who are candidates for intradetrusor onabotulinumtoxinA treatment. ASB increases the risk of UTI, but does not heighten the risk of urosepsis, hospitalization, or therapy failure. This study should lead to the reconsideration of current recommendations. © 2019 Wiley Periodicals, Inc.