Recent surveillance reports from Europe and the United States show an increase in syphilis cases. Accurate epidemiological information about the distribution of syphilis is important for targeting screening and intervention programmes. The German syphilis notification system changed in 2001 from physician to laboratory-based reporting, which is complemented by a newly introduced sexually transmitted infection (STI) sentinel system. After reaching an all time low during the 1990s, syphilis notifications have increased significantly since 2001, coinciding with the introduction of the new reporting system. However, the increased reported incidence is reflecting a true rise in the number of cases and is not predominantly determined by more underreporting through the previous reporting system. The increase reflects syphilis outbreaks among men who have sex with men (MSM). The first of these outbreaks was observed in Hamburg in 1997. In 2003, incidence in men was ten times higher than in women. An estimated 75% of syphilis cases are currently diagnosed among MSM. A high proportion (according to sentinel data, up to 50%) of MSM diagnosed with syphilis are HIV positive. The continuously high number of syphilis cases diagnosed among heterosexuals in Germany in recent years compared with other western European countries may reflect the higher population movement between Germany and syphilis high incidence regions in south-east and eastern Europe.