Background: Men who have sex with men (MSM) are disproportionally affected by sexually transmitted infections (STI). STI are often extragenital and asymptomatic. Both can delay diagnosis and treatment. Approval of HIV preexposure prophylaxis (PrEP) might have influenced sexual behaviour and STI-prevalence of HIV-MSM. We estimated STI-prevalence and risk factors amongst HIV-and HIV+ MSM in Germany to plan effective interventions. Methods: We conducted a nationwide, cross-sectional study between February and July 2018. Thirteen MSMfriendly STI-practices screened MSM for Chlamydia trachomatis (CT), Mycoplasma genitalium (MG), Neisseria gonorrhea (NG), and Trichomonas vaginalis (TV) using self-collected rectal and pharyngeal swabs, and urine samples. APTIMA™ STI-assays (Hologic™ Inc., San Diego, USA) were used for diagnostics, and samples were not pooled. We collected information on socio-demographics, HIV-status, clinical symptoms, sexual behaviour within the last 6 months, and PrEP use. We combined HIV status and PrEP use for defining risk groups, and used directed acyclic graphs and multivariable logistic regression to identify risk factors for STI. Results: Two thousand three hundred three MSM were included: 50.5% HIV+, median age 39 [18-79] years. Median number of male sex partners within the last 6 months was five. Sex without condom was reported by 73.6%, use of party drugs by 44.6%. 80.3% had a STI history, 32.2% of STI+ MSM reported STI-related symptoms. 27.6% of HIV-MSM used PrEP.