A comparative retrospective cohort study was performed to evaluate the influence of hospital-acquired infection (HAI) in neonates on additional charges and hospital stay. Neonates admitted between October 1993 and discharged alive before December 1995 at the neonatal intensive care unit of a university hospital were studied. Of 515 neonates, 69 (13%) had one or more HAI; 45 (20 with proven HAI, 25 with suspected HAI) were matched to 45 controls. After matching for gestational age, surgery artificial ventilation and patent ductus arteriosus, central vascular catheter utilization was the only factor significantly associated with HAI. Charges were obtained from hospital discharge abstracts and the duration of hospitalization from patients' files. The mean additional length of hospital stay; in neonates with HAI nas 24 days (54 days vs. 30 days, P=0.002) but did not differ significantly in patients with proven or suspected HAI (67 days vs. 51 days, P>0.05). The mean extra charges for patients with a HAI were 11750 EURO (pound 9635). Accommodation accounted for 72%, fees for 22%, pharmaceuticals for 5% and ancillary items for 1% of these extra charges. The mean charges per day were similar for controls [443 EURO (pound 363)] and HAI patients [453 EURO (pound 372)]. O Overall charges and charges per day. were similar for neonates with proven and suspected HAI. (C) 2001 The Hospital Infection Society.