AIMS: To investigate the relationship between urinary flow rate and ejaculation in healthy young men.METHODS: Young men were voluntarily enrolled in the study. All subjects were healthy, and sexually active, without neurological diseases, genital, or urethral surgery and they were not under any medications. Subjects were evaluated with ultrasound, uroflowmetry, and post-void residual urine (PVR) measurement. All subjects were followed for 22 days (T) with daily uroflowmetry, and were instructed to ejaculate only on specific days (0, 6 and 22) during the study period. On days 0, 6 and 22 uroflow measurements were performed between 2 and 6  hr following ejaculation. Uroflowmetry parameters before and after ejaculation and during abstinence were compared. Data presented a non-normal distribution and the non-parametric Wilcoxon-match-paired test and Kruskal-Wallis test were used for statistical analysis.RESULTS: 18 subjects (mean age 27.4 years) completed the study. A total of 414 uroflow charts were collected. A statistical significant increase in Qmax was observed after ejaculation (T-1 Qmax: 22.7  ±  5.4 vs. T0 Qmax: 25.7 ± 8, P = 0.002; T5 Qmax 23.2  ±  5.4 vs. T6 Qmax 25.4  ±  8, P = 0.031; T21 Qmax 21  ±  4.8 vs. T22 Qmax 24.5  ±  7.9, P = 0.031). Sexual abstinence resulted in a progressive, statistically significant decline in Qmax rates (T0 Qmax 25.7  ±  8 vs. T5 23.2 ± 5.4 P = 0.035; T6 Qmax 25.4  ±  8 vs. T21 Qmax 21  ±  4.8, P = 0.01). PVR did not change during the study period.CONCLUSIONS: Our results suggest that in young healthy men micturition might be influenced by ejaculation. Our findings, if confirmed in larger series of patients with LUTS, should support that sexual status and activity could represent an important confounding factor in the interpretation of uroflowmetry traces.