Benign prostatic hyperplasia (BPH) affects men with increasing frequency as they age. The course of BPH is highly variable and not all men develop symptoms.For most patients with mild symptoms of BPH, regular monitoring and reassessment (watchful waiting) are most appropriate. For those with moderate to severe symptoms, surgery [usually transurethral resection of the prostate (TURP)] or drug therapy (with finasteride or &agr;1-receptor antagonists such as terazosin) are most frequently used. Surgery is indicated for men with complicated BPH.Both terazosin and finasteride reduce voiding (obstructive) and total symptom scores and improve parameters of urinary function such as peak urinary flow rates in men with symptomatic BPH. However, results from a comparative trial of these agents show terazosin to be more effective than finasteride in reducing symptoms and increasing urinary flow rates. Although the study has been criticised for not stratifying patients by baseline prostate volumes and for the low mean prostate volumes of study participants, the findings have subsequently been confirmed in a subset of men with large prostates (> 50ml).In common with other &agr;1-receptor antagonists, terazosin reduces smooth muscle tone and contraction in the bladder neck and prostate, which results in a decrease in urethral pressure. The drug does not reduce prostate volume and efficacy is not influenced by prostate size. Terazosin has favourable effects on blood pressure and the lipid profile.Finasteride acts by inhibiting the 5&agr;-reductase enzyme in the prostate, thus reducing circulating levels of dihydrotestosterone, the androgen primarily responsible for prostatic enlargement. Consequently, finasteride reduces prostate volume and the drug has been thought to be most effective in men with a prostate volume ≥40 or 50ml; however, whether baseline prostate volume is an accurate predictor of response to pharmacotherapy has now been questioned. Finasteride has a slow onset of action compared with terazosin (≈6 months versus a few weeks), but preliminary evidence indicates that disease progression may be halted or reversed when finasteride is used long term (≥2 years). Furthermore, finasteride has been shown to reduce the incidence of acute urinary retention and surgical intervention associated with BPH.In men with symptomatic BPH, there are few clear-cut criteria for initiation of treatment or for predicting which treatment will be most beneficial. The long term costs and benefits of various treatment options remain to be fully determined. On the basis of available data, terazosin may be used in patients with moderate to severe symptomatic BPH irrespective of prostate size; this agent may be particularly useful in men with concomitant hypertension. Finasteride appears to be best limited to patients with a prostate volume ≥40 or 50ml. Symptomatic improvement appears to be greater with terazosin than with finasteride, whereas finasteride is the only agent, to date, which has been shown to halt or reverse disease progression and reduce surgical intervention and acute urinary retention in this patient group. In the final analysis, treatment decisions must be individualised and guided by clinical experience and judgement as well as patient preference.