Erectile dysfunction (ED) and obstructive sleep apnoea (OSA) are increasingly common conditions seen in primary and secondary care. With shared risk factors and associated comorbidities men often suffer with both. The aim of this study is to review the literature to consider why there is a correlation, and clinically how assessment and management of such patients could be adjusted. A structured review of current literature was performed using search terms 'erectile dysfunction' or 'erectile function' or 'Erection' or 'Sexual dysfunction' AND 'Sleep apnoea/apnea' or 'sleep disorder'. Descriptive analysis categorized results into: The association between OSA and ED; the pathophysiological hypotheses; the role of OSA treatment; and the role of ED treatment. Higher prevalence of ED in patients with OSA is demonstrated, particularly in men with more severe OSA disease, reaching 80% in some studies. However, the pathophysiological explanation remains unclear with a number of hypotheses researched. CPAP is the mainstay of treatment for OSA, and short and long-term benefits to sexual function are demonstrated in men with severe OSA from it's use. Further improvement in ED and quality of life can be achieved by additional PDE5 inhibitor therapy. With the increasing evidence base showing higher rates of ED in OSA patients there is certainly a role for clinicians in both OSA and ED clinics to enquire about each condition. A referral to their counterpart for consideration of combination treatment with CPAP and a PDE5 inhibitor for both of these problematic, life changing diseases is recommended-particularly in those with severe disease. Further investigation is needed to try and establish any pathophysiological link, and the impact of treatment in less severe cases.