Two landmark multi-centre trials, MTOPS and PCPT, have shown that finasteride is an effective treatment of micturitional disorders due to benign prostatic hyperplasia, reducing the clinical progression of BPH. The MTOPS trial showed for the first time the medium term benefit which patients could obtain with combined treatment in reducing the risks of the symptoms aggravating, urinary retention, surgery, renal failure, infection and incontinence. The PCPT trial showed finasteride to be beneficial in reducing the clinical progression of BPH. These trials defined risk factors for progression: PSA concentration over 1.6 ng/ml, prostate volume over 31 ml, urine output less than 10.6 ml/sec, age over 62 years old and post-micturitional residual volume of more than 39 ml. A 19% reduction in prostatic volume was also seen at 4.5 years on finastéride compared to a 24% increase on placebo. According to recommendations, the use of combined treatment is reserved for patients with moderate to severe urinary disorders after failure of first line monotherapy.