Coagulase-negative staphylococci (CoNS) are the most common bacteria isolated from infections following cardiac surgery. CoNS display various virulence factors, such as toxins, adhesive proteins and biofilm production. The Staphylococcus epidermidis surface (Ses) protein I and the ica operon encoding the polysaccharide intercellular adhesin (PIA) are discussed in more detail. Although several of these virulence factors are prevalent among CoNS isolates causing sternal wound infections, they do not represent a prerequisite for causing an infection and that emphasizes that host factors may be as important.