The microbiology of wounds is a key determinant in healing and clinicians generally accept that a level of microbial (ie, bacterial) growth greater than 100,000 viable organisms per gram of tissue can be used to diagnose infection. Although other factors that predispose a wound to infection are widely recognized, today's wound care practitioners are influenced primarily by the 10 5 guideline, with treatment being based on the microbial count in deep or superficial tissue. However, to appropriately manage microbially challenged wounds (eg, heavily colonized and clinically infected), a more balanced awareness of the broader issues relating to micro-organisms and wounds is needed. The types of micro-organisms, their interactions with each other and with the wound environment, the local conditions, and host resistance are all key factors that collectively influence healing. From a microbiological perspective, successful wound healing is dependent on maintaining a host-manageable bioburden. If local conditions favor microbial growth, a wound may fail to heal and become infected, requiring topical antiseptics or antibiotics to supplement the host inflammatory response and restore balance in favor of the host. This paper provides a critical examination of the 10 5 guideline to enhance clinician understanding and utilization of a commonly applied diagnostic consideration.