The Authors study the incidence of gram-negative fermentative and non-fermentative bacilli in an Intensive Care Division according to the following microbial contamination indexes: Air Microbic Index; Staff Index; Patient Index; Equipment Index. The collected data show that some air microbic factors and part of the complementary equipment to intensive care are particularly infected by gram-negative germs Germs such as Pseudomonas Acinetobacter and mainly bacilli of K.E.S. group.