Towards the end of the last century some sexually transmitted infections (STI), which had been held to be almost extinct, have seen an unexpected resurgence. They mainly present as urethritis, genital ulcers or genital warts and must always be diagnosed and treated so as to prevent further transmission. The main causes of urethritis are gonorrhea and chlamydia, the latter can also cause only minor symptoms. The pathogen should always be diagnosed with direct microscopy of a urethral smear as well as culture or PCR. Antibiotic treatment is usually straightforward. Genital ulcer disease can be caused by a wide spectrum of bacteria and viruses as well as non-infectious causes. It is significant as it can facilitate the transmission of HIV. The most frequent cause is herpes simplex virus which usually presents itself with painful ulcers and a recurrent course. Syphilis occurs in different clinical stages. The first stage is usually a painless ulcer, it can be difficult to diagnose and is often missed. In the second stage, characterised by a rash and a variety of classical symptoms such as condylomata lata, the diagnosis can be made with various serologic tests. Long-acting penicillin remains the treatment of choice. Genital warts are a consequence of HPV infection and can usually easily be diagnosed based on the clinical picture. Some high-risk HPV types can lead to malignant transformation, especially in immunocompromised patients. Besides different destructive therapeutic modalities, some effective treatments can be applied locally by patients themselves.