A prospective collection of positive antimicrobial cultures was performed over 12 consecutive months in the medical intensive care unit of a cancer hospital. In all, 144 infections and 163 pathogens were documented during 87 of the 528 admissions. Lung, urinary, ENT (ear, nose and throat) infections and bacteraemia were the most frequently documented. Staphylococcus species, Streptococcus species, Escherichia coli, Klebsiella species and Pseudomonas species were the most common pathogens. Gram-positive strains were observed predominantly during monomicrobial bacteraemia (48.9%). Methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) were found in 58% and 92% of the isolated strains respectively. No particular outbreak was identified. A further prospective study will be necessary to evaluate the impact of the antibiotic use on the selection of resistant strains in our ICU.