Abstract Ralstonia mannitolilytica, a Gram-negative bacterium, is rarely isolated in clinical laboratories. It has been associated with outbreaks due to its ability to survive in liquid media and hospital devices. We describe three cases of bacteremia caused by R. mannitolilytica in a neonatal intensive care unit in Curitiba, Southern Brazil. All isolates presented the same PFGE profile. The common source of infection was undetected in surveillance cultures for the outbreak survey. All patients received antimicrobial treatment and were discharged from the maternity. Due to the characteristics of the microorganism, clinicians and microbiologists should pay attention to the emergence of Ralstonia spp. infections.