Benign prostate obstruction (BPO) can be treated with a range of laser treatments using different laser systems and applications. Transurethral laser treatment is considered to be an alternative treatment to transurethral resection of the prostate (TURP). The latest guidelines of the European Association of Urology recommend 532-nm GreenLight laser vaporisation of the prostate and thulium laser enucleation as alternatives to TURP. For further investigation of the efficacy of GreenLight and thulium laser in treating BPH, the investigators organize a prospective randomised control study. The investigators will enrol 100 patients with BPO, treated with either GreenLight laser or thulium laser prostatectomy, and compare their safety and efficacy.