In Germany, the number of reported syphilis cases increased between 11% and 22% per year between 2010 and 2014. We analysed syphilis surveillance data and data of four behavioural surveys on men who have sex with men (MSM) in Germany (2003, 2007, 2010, 2013) to assess if this rise is ongoing and to find possible explanations for it. Syphilis notifications increased in 2015 by 19% to a total of 6,834. This was mainly due to increasing notifications in MSM of all age groups in larger German cities. Data from the behavioural surveys on MSM in Germany showed a simultaneous increase of selective condom use as HIV-status-bases risk management strategy and the number of syphilis cases. MSM diagnosed with HIV reported condomless anal intercourse with non-steady partners more frequent than MSM not diagnosed with HIV or untested for HIV, but the latter also reported higher frequencies of this behaviour in the more recent surveys. Transmission in HIV-positive MSM probably plays an important, but not exclusive role, for the syphilis dynamics in Germany. A risk adapted routine screening for sexually active MSM and potentially innovative approaches to increase early screening and treatment of syphilis such as internet counselling, home sampling, home testing and broadening venue-based (rapid) testing, should be critically evaluated to effectively reduce syphilis infections.