The microbial colonization and the associated risk of respiratory infection during the application of a multiple-use closed-system suction catheter (CSSC) and a single-use open-system suction catheter (OSSC) on liver transplant patients was evaluated in this preliminary study. The cost differential for the two systems was also compared. Twenty post-orthotopic liver transplant (OLTx) patients who were mechanically ventilated via an endotracheal (ET) tube were studied. Ten subjects were randomly allocated ET suction by the CSSC and 10 with OSSC. Both groups were similar according to age, sex, clinical severity, presence of a naso-gastric tube, use of H2 antagonists and antibiotics used. Standard protocols were followed to intubate and suction the patients and to change ventilatory equipment. Suctioning performed with the CSSC did not significantly increase the risk of microbial colonization of the respiratory tract. Similarly there was no apparent difference in the incidence of nosocomial pneumonia between the two suction systems, based on the microbiological and clinical data. The mean daily cost of using the CSSC compared to the OSSC was 11.6 times higher. This may be balanced by a reduction in nursing time and reduced risk of spread of infection associated with the CSSC.