Background: Syphilis is a re-emerging infection. Sexually transmitted infection (STI) clinics and GPs are important providers of STI care in the Netherlands. The role of GPs in syphilis care is assumed to be small, since most men who have sex with men (MSM) visit STI clinics for STI care. Aim: To explore the role of GPs in the diagnosis and treatment of syphilis. Design & setting: Data on syphilis diagnostics by GPs in Amsterdam between 2011 and 2017 were retrieved from laboratories, covering 90% of the GPs. The study also used the academic GPs’ network database to explore the management of syphilis by GPs between 2013 and 2018. Method: Syphilis tests requested by GPs were analysed and compared with annual reports of the STI clinic. Patients with an International Classification of Primary Care-1 (ICPC-1) syphilis code were identified in the GP database. Cases diagnosed by the GP were evaluated whether they were treated by the GP or referred to secondary care. Results: In the laboratory database, GPs had diagnosed syphilis 522 times, compared with 2515 times by the STI clinics. Based on the 90% coverage of GPs, the contribution of all Amsterdam’s GPs was 19% of the total number of diagnoses. Consequently, the annual incidence of syphilis diagnosed by the GP was 10.2 per 100 000 inhabitants. Of the 43 cases identified in the GP database, six (14.0%) were referred and 33 (76.7%) were treated by a GP. Conclusion: Although for an individual GP, syphilis is rare to diagnose, GPs in Amsterdam do contribute to the rate of syphilis diagnosis and appear to treat the majority of cases that they have diagnosed.