We aimed to study the prevalence, characteristics and risk factors of asymptomatic sexually transmitted infections (STIs) in HIV-infected men who have sex with men (MSM). We conducted a prospective cross-sectional study, including asymptomatic HIV-infected MSM attending regular visits between December 2014 and December 2017. Of the 301 patients included, 60 patients (19.9%) presented at least one STI. The most common STI was syphilis (33 of 69 STIs), followed by chlamydia (19 of 69), gonorrhoea (10 of 69), hepatitis C virus (4 of 69) and lymphogranuloma venereum (3 of 69). Illicit drug use during sex was the only variable significantly associated with the presence of an STI on multivariate analysis (OR 2.13; 95% CI 1.17–3.89). We were unable to identify a subgroup of patients where we could potentially avoid STI screening. Our findings support current guidelines that recommend routine screening for all HIV-infected MSM regardless of their self-reported sexual history.