Background: Lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) and erectile dysfunction (ED) are common disorders whose prevalence increases with advancing age We aimed to compare between efficacy of tadalafil 5 mg and tamsulosin 0.4mg monotherapy vs combined therapy in treatment of lower urinary tract symptoms of benign prostatic hyperplasia. Patient and methods: This randomised, single-blind, paralleled group clinical trial was done on 60 patients with ED and LUTS due to BPH were included in a prospective study and Received treatment. Group A received 5 mg/daily tadalafil; Group B received 0.4 mg/daily tamsulosin; Group C receieved a combination of 0.4 mg/daily tamsulosin and 5 mg/daily tadalafil. The three groups were been compared according to International prostate symptom score (IPSS), International index of erectile dysfunction (IIEF) score and maximal urinary flow rate (Qmax) Results: Post-void residual level was significantly different before and after the treatment, except for group A. Also, this group had no meaningful difference compared to the other groups in this regard (P > 0.05). There were significant differences between pre- and post-treatment international prostate symptom scores in each group (P < 0.05). Conclusion: combination therapy with tadalafil and tamsu- losin is recommended because of its good outcomes in erectile dysfunction.