These guidelines provide an overview for investigating and managing infants at risk of congenital syphilis in the Northern Territory of Australia. Risk is determined by the mother's syphilis serology and treatment history. Infants are categorized as no risk, low risk, or high risk. Testing and treatment are tailored based on risk level, with high risk infants receiving more extensive investigations and management through follow up coordinated by local health departments. Interpreting syphilis serology requires knowledge of current clinical information as well as past test results and treatment, and assistance is available from sexual health experts.