Haemophilus influenzae is a rare cause of peritonitis in patients on peritoneal dialysis (PD). We report a case of peritonitis due to non-typeable H. influenzae in a 5-year-old girl on automated PD. The patient was successfully treated with intraperitoneal cefepime and cefazolin. The isolate was multilocus sequence type 3 and contained the hmw and hia genes but was IS1016-negative. Seven of the eight reported cases were female, indicating that sex-associated factors may be important in H. influenzae peritonitis in patients on PD. Determination of the pathogenesis of PD-associated H. influenzae peritonitis requires gene analysis and a swab sample from the vaginal introitus.