Study to Characterise the Effect of Tamsulosin on Lower Urinary Tract Symptoms (LUTS) and Detrusor Motor Activity in Patients Affected by Benign Prostatic Hyperplasia (BPH) and Storage Urinary Symptoms

Inclusion Criteria: * Male outpatients aged 50-80 years * LUTS suggestive of BPH * Medical history: storage symptoms (frequency, urgency) for at least 6 months * Urinary Chart: * At least 8 micturitions per 24 hours on average, over the week of the screening period (check urinary chart at Visit 2) * Urgency (strong desire to void): at least once per 24 hours on average, over the week of the screening period (check urinary chart at Visit 2) * I-PSS ≥ 13 at randomisation (Visit 3) * Qmax: \> 4 ml/sec at randomisation (Visit 3), with a voiding volume of at least 150 ml * Prostate Specific Antigen (PSA) \< 2.5 ng/ml or between 2.5 and 10 ng/ml, if cancer is ruled out with the usual procedures of each centre (Visit 1; results before Visit 3) * Written Informed Consent for participation to the study Exclusion Criteria: * Patients with a known history or a diagnosis at the time of the screening visit (Visit 1) of the following conditions: * Urological disturbances * Medical history of pelvic surgery * Palpable bladder at the physical examination, or residue urinary volume \> 400 ml * Known neurological bladder disorder * Bladder neck stenosis * Urethral stricture * Bladder or prostatic cancer * Bladder stone * Severe diverticulum of the bladder * Symptomatic urinary tract infection during last month, or recurrent urinary tract infections (more than 2 during last year) * Haematuria of unknown origin * Diseases which may affect micturition (i.e., diabetes mellitus) * Cardiovascular diseases (if they occurred in the last 6 months) * Myocardial infarction * Instable angina * Clinically significant ventricular arrhythmias * Heart failure (NYHA classes III/IV) * Orthostatic hypotension * Cerebral stroke * Neurological diseases (if their severity might compromise the correct performance of the trial) * Senile dementia * Multiple sclerosis * Parkinson's disease * Psychiatric disturbances * Hepatic or renal insufficiency (biochemistry values 15% outside normal lab ranges, being regarded as clinically relevant by the investigator) * Clinically significant abnormality in the haematological, blood chemistry and urinary values evidenced on the samples taken at the screening visit (Visit 1) * Patients who are taking or have been taking α-blockers for BPH or for hypertension, or phytotherapy for BPH within the previous 6 weeks * Patients who were taking or have been taking: * α-blockers for BPH or for hypertension within the previous 4 weeks * phytotherapy for BPH or mepartricin within the previous 4 weeks * finasteride within the previous 6 months * anticholinergics within the previous 4 weeks * antidiuretics within the previous 4 weeks * concomitant drugs which may influence the pharmacodynamic or pharmacokinetic properties of tamsulosin. In particular: α-blockers and mixed α-β-blockers, α- agonists, anti-cholinergics * Patients who are or have been taking part in a clinical study within the previous 3 months * Patients who have had hypersensitivity or allergic reactions to previously prescribed α- blocker(s) * Patients judged by the investigator to be inappropriate for inclusion in the study