Objectives Our study aims to describe the association between SLE and sexual function, analysing demographic variables, comorbidities and other disease-related factors. As an exploratory objective, the impact of asking about sexual function during outpatient consultation was evaluated. Methods From 2018 to 2019, we invited sexually active men diagnosed with SLE to complete questionnaires that evaluated their sexual function and quality of life. Additionally, patients were asked if they believed they had sexual dysfunction, whether they would be interested in receiving specialized sexual care, and if they considered SLE to be detrimental to their sexual function. Epidemiological and disease-related data were retrieved from the patients’ clinical records. Results We included 124 men with SLE. Twenty-two (18%) patients answered positively when asked if they believed they had sexual dysfunction. These patients had lower overall erectile function scores and lower physical function scores than those who did not consider they had sexual dysfunction. In the multivariable analysis, factors that were associated with better sexual function were high physical function (B = 0.126, p = .031), lower BMI (B = 0.53, p = .010) and the patient’s perception of normal sexual function (B = 13.0, p < .001). Comorbidities associated with worse sexual function were type 2 diabetes (B = −8.1, p = .017) and a history of thrombosis (B = −5.12, p = .019). Conclusion Sexual function of male patients with SLE is impaired, independently of disease activity, chronic disease damage or pharmacological treatment. A simple question about perception of sexual function in the outpatient clinic can be used to help determine which patients could benefit from a multidisciplinary intervention to improve sexual health.