The number of people living with HIV infection has been increasing since the mid 1990s and is expected to rise further in the coming years. The HIV epidemic in Germany is still most affected by developments in the group of men who have sex with men (MSM). In this group, the number of newly diagnosed HIV infections has increased in recent years especially in large cities. Despite increased efforts to motivate HIV-infected people, who were not previously diagnosed, to be tested as early as possible and to seek medical treatment, the number of undiagnosed HIV-infected persons has increased. There are more people infected with HIV than those who have been tested positive for HIV and subsequently receive antiretroviral treatment. However, early testing and treatment alone are not sufficient to effectively contain the infection. Increased efforts are required to more effectively prevent new HIV infections by combining all the available options. In Germany as in all other developed countries, a stronger increase in the number of syphilis infections among MSM is reported, which is primarily due to a higher willingness to risk unprotected contacts, whereby the risk of HIV infection is also increased. The public prevention messages available for HIV are only partially effective against syphilis. More frequent examinations and optimized therapy management are necessary in addition to the use of condoms to prevent the spread of syphilis, gonorrhea, and Chlamydia trachomatis. Sustainable containment of new HIV infections must, therefore, be accompanied by both containment of sexually transmitted infections (STI) and use of public prevention messages for HIV/STI.