Uroflowmetry is a non invasive objective criterion for the evaluation of micturition. The values depend on resistance to voiding, but also detrusor pressure. Correct interpretation must take into account the limits of the examination, related to voiding volume, number of micturitions, age, individual factors, and circadian variations. Some artefacts, such as the initial peak or abdominal straining, induce a difference between automatic reading and manual reading, justifying comparison of the result displayed with the appearance of the curve. Uroflowmetry can detect dysuria, which may be poorly perceived or even unknown to the subjects themselves. It also completes the data of symptom scores. It is a good criterion for assessment of the results of treatment, but is insufficient, on its own, to define surgical indications. There is no strict correlation between flow rate and residual volume.