Malnutrition alone may provoke considerable immune alterations, mainly in the immunocellular function, and in particular in the T lymphocyte and macrophage-monocytic function. This gives rise to an increase in proneness to infections, which in patients subjected to bone marrow transplants, will be increased by the intense neutropenia suffered by them. This study shows the greater incidence of infection among badly nourished patients compared to nourished patients. It was also observed that short bouts of high temperature mainly occurred in a subgroup of patients with an acceptable nutritional level, which in our opinion was the cause for none of them developing the infectious illness. Finally, one of the germs most often found in these patients is Staphylococcus epidermis, and the most common method of entry is through the catheters used in the administration of medicines and artificial nutrition. Emphasis is placed on the role played by nursing in preventing this type of infection.