Backround: The pelvic floor muscles are active in normal erectile function. Therefore, it was hypothesised that weak pelvic,floor muscles could be a cause of erectile dysfunction. Aims. To compare the efficacy of pelvic floor muscle exercises and manometric biofeedback with lifestyle changes for men with erectile dysfunction. Design of study: Randomised controlled trial. Setting: The Somerset Nuffield Hospital, Taunton, united Kingdom. Method: Fifty-five men with erectile dysfunction (median age 59.2 years; range 22-78 years) were enrolled from a local urology clinic. Of these, 28 participants were randomised to an intervention group and engaged in pelvicfibor exercises, as well as receiving biofeedback and suggestions for lifestyle changes. Twenty-seven controls were solely advised on lifestyle changes. Baseline, 3- and 6-month assessments were: erectile function domain of International Index of Erectile Function (IIEF), Partner's International Index of Erectile Function (PIIEF), Erectile Dysfunction-Effect on Quality of Life (ED-EQoL), anal manometry, digital anal measurements, and clinical assessment by an assessor blind to treatment allocation. After,3 months, the control group were transferred to the active arm. control group were trans Results. At 3 months, compared with controls, men in the intervention group showed significant mean increases in the erectile,function domain of the IIEF (6.74 points, P = 0.004); anal pressure (44.16 cmH(2)O, P<0.001); and digital anal grades (1. 5 grades, P<0.001). All showed further improvement in these outcomes at 6 months. Similar benefits were seen in men of the control arm after transfer to active treatment. A total of 22 (40.0%) participants attained normal function, 19 (34.5%) participants had improved erectile function, and 14 (25.596) participants failed to improve. Conclusion: Pelvic floor muscle exercises and biofeedback are an effective treatment for men with erectile dysfunction,