Syphilis is caused by a spirochaete bacterium called Treponema pallidum. Vertical transmission of spirochaetes can lead to congenital infection of the fetus in pregnant women who are inadequately treated or not treated at all, causing various clinical manifestations including stillbirth and neonatal death, cutaneous and visceral manifestations, or asymptomatic infection. We present a severe case of syphilis in a 3-month-old boy with skin lesions, portal hypertension, and anaemia. Because the mother was tested negative for syphilis antibodies at 16 weeks of gestation, a diagnosis of congenital syphilis was initially not considered. This case shows that transmission of T pallidum can still occur in high-income countries with a high rate of antenatal screening. Early recognition might be hampered if physicians do not consider congenital syphilis as a possible diagnosis. Congenital syphilis should be considered in any severe and diagnostically challenging infectious disease case, even in the context of negative antenatal screening.