OBJECTIVE: To highlight to the fact that some newborns are not identified as having congenital syphilis, and will present to an emergency room within a few months with a severe disease. METHOD: Review of the charts concerning 3 patients with congenital syphilis, as well as review of the literature using Medline and Lilacs databases, covering the period from 1988 to 1999. RESULTS: We describe the case of 3 infants whose diagnosis of congenital syphilis was only established after the neonatal period, when they presented to the emergency room and were admitted to the pediatric intensive care unit. The first patient had neurosyphilis and nephrotic syndrome, the second had neurosyphilis, and the third had hepatitis. We discuss the clinical aspects of the cases, and comment on other clinical manifestations of congenital syphilis that should be within the purview of pediatric emergency medicine. We analyze the reasons for the failure to diagnose syphilis at birth, and describe some risk factors for gestational syphilis. CONCLUSIONS: Considering the rising incidence of syphilis in Brazil, and the possibility that the congenital infections are not recognized at birth, emergency physicians must keep a high degree of suspicion and an awareness of maternal risk factors, prenatal serology pitfalls, as well as of the several clinical presentations of congenital syphilis that can develop in the first months of life.