The role that different types of mattresses play in preventing pressure ulcer (PU) development in intensive care unit (ICU) patients is unclear. The effect of mattresses on the development of PUs was retrospectively investigated in 8,956 ICU patients in a clinical observational study over a 6-year period. The annual PU incidence decreased from 11.1% to 3.7% during the study period, although the severity of the patients’ medical condition did not change. The four most prevalent support surfaces deployed as a first mattress were foam; alternating air; dynamic, low pressure mattress system; and the computerised, individually and precisely adaptive minimum pressure air mattress system (MPA). The significant reduction in PU incidence was concomitant with a reduction in foam mattresses from 53% to 4% and an increase in non-alternating MPA mattresses as the first mattress from 0% to 57.2%. The incident of PUs among patients on MPAs was significantly lower than on any of the other mattresses.