Currently the debate on the role of urodynamic tests in the preoperative evaluation of female stress urinary incontinence is alight. Although urodynamic investigation (UDI) has been considered mandatory before surgery in all female patients affected by stress urinary incontinence, nowadays international guidelines are more cautious. Literature on this topic has been reviewed in order to clarify the role of UDI before surgery for "complicated" and "uncomplicated" stress urinary incontinence in female patients. We focused on if and how UDI may improve clinical outcomes and alter clinical decision making. In conclusion, we believe that in most patients (the "complicated" ones) the role of UDI has not been fully evaluated. In "uncomplicated" cases, pretreatment UDI might not improve clinical outcomes but it could give important informations (voiding dysfunction in about 10% of cases) offering a valuable guide to the surgeon and to the patient. Interestingly though, UDI could alter clinical decision making being a valuable tool in counseling our patients with the aim of cure their symptoms, never risking of worsening them or causing further discomfort.