The author's studied the adherence ability of Enterococcus faecium SF 68 compared to that of Enterococcus faecalis IM 11f, on various substrates: vascular catheters and cardiac valves of rabbit, immunodepressed rats and diabetic rats. The bacterial adherence test was calculated by the number of bacteria adhered for microscopic field enlarged to 2000. The data obtained by scanning electron microscope SEM (Cambridge Stereoscan 150 MK2) revealed a different adherence action of the two germs on the various substrates. All the adherence tests showed a higher and uniform adherence activity of E. faecalis compared to that of E. faecium.