This study was designed to verify if breast milk collected at home is appropriate for raw consumption by neonates in a Brazilian public neonatal intensive care unit (NICU). From May 1998 to February 2000, microbiological characteristics of breast milk samples collected at home were analyzed. The milk samples were considered appropriate for raw consumption if mesophilic bacteria count was < 2500 CFU/mL and potential pathogens were not detected. Of 90 milk samples collected from 32 mothers of hospitalized neonates, 36 (40%) were rejected because of potentially pathogenic bacteria (72.2%), mesophilic bacteria count > or = 2500 CFU/mL (13.9%), and both conditions (13.9%). The most frequent nonpathogenic and potentially pathogenic bacteria isolated were Staphylococcus coagulase negative and Klebsiella pneumoniae, respectively. Using univariate analysis, demographic, socioeconomic, educational, and house characteristics were not found to be associated with milk contamination. Breast milk collected at home may not be appropriate for raw consumption in Brazilian NICUs. Pasteurization could improve its microbiological quality. Further studies are needed.