The aetiology of bladder outlet obstruction (BOO) is diverse, and anatomic causes often induce a functional abnormality that remains somewhat unique for each individual, regardless of gender. A full appreciation of the possible aetiologies of obstruction is necessary to identify overt and more subtle scenarios. Individualised symptom appraisal is a crucial component of evaluation to assess the magnitude of the impact of the symptoms. The combination of bladder diary, flow rates, and postvoid residual volume with urodynamic and pressure flow evaluation is now the gold standard.