Malassezia spp. is a lipophilic yeast considered to be a normal component of the human skin flora. It has been associated with sepsis in patients receiving intravenous infusion of lipid emulsions through central venous catheters (CVC). Current evidence indicates a high rate of skin colonization in healthy adults, in contrast with the low rate of colonization in prepubertal children. Of note is the high prevalence of colonized infants in the neonatal intensive care unit (NICU).We performed a prospective open observational study of colonization in all infants admitted to the NICU during a nine-month period (October 1997-June 1998). Length of stay in the unit, birthweight and the use of CVC for parenteral fat infusion were evaluated.Seventy-seven neonates were included in the study. The mean length of stay in the NICU was 24 days. A total of 63.6 % weighed less than 2,500 g at birth and 72 % were given parenteral nutrition supplemented with fat emulsion through a CVC. The overall rate of colonization in the unit was 41.5 and 75 % of the patients became colonized within the first two weeks of admission.These data emphasize the need for preventive measures to reduce the transmission of these yeasts in the NICU and to prevent the occurrence of neonatal sepsis due to Malassezia spp. in immunologically immature infants.