Two newborns had hematogenous pyarthrosis due to Haemophilus influenzae. One infant had signs of sepsis and dactylitis involving several fingers and toes. She also developed a soft tissue abscess, meningitis, and a septic hip, and was found to be infected with a nontypable organism. In the second infant, a shoulder traumatized at birth became infected with a type b strain. In both cases, the patients were successfully treated, but delays occurred in selecting the optimal therapeutic agent because of failure to appreciate that Haemophilus may cause systemic infection in the newborn. In the first infant the source of the infection was identified as the mother's endocervical canal. This patient is also of interest because in contrast to previous reports of Haemophilus infection in the newborn, bactericidal activity was present in the maternal serum.