Purpose: To determine the relationship that exists between certified nurses’ knowledge about bio-security measuresand its application in medical service at the “Hipólito Unanue” General Hospital for the 2009. Methodology: Thepresent study was descriptive, correlational, and cross-sectional; the sample for this study was obtained from 26certified nurses who work for medical service assistant area, utilizing a questionnaire and an observation guide asresearch instruments. The Windows 12 Statistical SPSS software was used for data processing. Results: 53.8% ofcertified nurses have an excellent knowledge level, followed by 34.6% who hold a good knowledge level and only11.5% hold an intermediate knowledge level. The results related to the application of the bio-security measuresindicate that 84.6% of the certified nurses perform a good application of these measures and 15.4% apply it i...