Aims: To determine lower urinary tract symptoms (LUTS) prevalence and urodynamic findings in amyotrophic lateral sclerosis (ALS) patients treated in our hospital. Methods: Cross-sectional and descriptive study on a cohort of ALS patients. Validated questionnaires (ICIQ-SF, IPSS, and OAB-V8) were self-administered in order to evaluate the presence of LUTS. Symptoms were classified as clinically significant (csLUTS), if any of following scores, IPSS>7, ICIQ-SF>0, or OAB-V88, were present. Urodynamic study was offered to csLUTS patients. Physical examination and prostate ultrasound were also performed. Results: Fifty five of seventy nine (70%) ALS patients accepted to participate in the study. Only 24/55 (43.6%) patients met criteria for csLUTS and 13 patients reported urgency urinary incontinence (26.3%). Most of csLUTS patients complained of mixed symptoms (82.6%). QoL measured by IPSS was 2.11.5, 20% scoring as mostly dissatisfied or unhappy. Average QoL ICIQ-SF scoring was 3.17 +/- 3, 33% complained of moderate to severe bother. Ten of twenty four (41.7%) csLUTS patients consented to UDS. The most frequent finding was detrusor overactivity with obstruction due to non-relaxing external sphincter (five patients) or bladder neck (two patients). Two patients showed normal bladder filling but non-relaxing external sphincter during voiding. UDS was normal in one patient. Conclusions: In this small pilot study we found a high prevalence of csLUTS in ALS which are mainly related to a combination of voiding and storage symptoms. In most patients, symptoms are caused by overactive detrusor combined with non-relaxing sphincter. Severity of symptoms and impact in QoL is only moderate but in a subset of patients can be considerable. Neurourol. Urodynam. 36:626-631, 2017. (c) 2016 Wiley Periodicals, Inc.