<b><i>Introduction:</i></b> We compared voided volumes (VV) at voiding diaries (VD) and at uroflowmetry (UF) in men with lower urinary tract symptoms (LUTS). <b><i>Methods:</i></b> This was a prospective, multicenter study. In a cohort of males with LUTS, VV reported in 3-day VD was compared to VV recorded at UF. Demographic data were analyzed. The patients were stratified according to VV. A sub-analysis dividing males by age strata was also performed. <b><i>Results:</i></b> We enrolled 169 patients. Mean VV were higher at UF than at VD in the entire population and in each group, stratified by age. VV significantly decreased with aging. Males with the lowest threshold difference (50 mL) were 29%, with a moderate threshold difference (&#x3c;100 mL) 55.6%, with an intermediate threshold difference 49.1% (51–150 mL), whereas 21.9% of men had a large threshold difference (&#x3e;150 mL). <b><i>Discussion/Conclusion:</i></b> VV correlation between VD and UF was poor. A large part of men performed UF with VV which were poorly comparable to the habitual VV assessed by 3-day VD. Therefore, our results indicate the relevance to obtain more than 1 UF in these patients.