Purpose: The purpose of this study was to examine the under-reporting rate and related factors after blood and body fluid (BBF) exposure among hospital employees. Methods: Fifteen hundred l employees were conveniently sampled from ten university and acute care hospitals. The survey questionnaire consisted of 37 items. Data were collected from September 10 to November 30, 2008. Results: The survey response rate was 88.7%. The 47.9% (638/1,331) of hospital employees were exposed to BBF and the mean number of exposure was $4.7{pm}5.942$ within the previous year. Under-reporting rate after BBF exposure was 69.4% (443/638). By multi-variate logistic regression analysis, the exposure number, exposure type, infectious disease and hospital were independently related to the under-reporting of BBF among hospital employees. Conclusion: The under-reporting rate after being exposed to blood and body fluids was relatively high. To address this problem, educational programs are needed to decrease the under-reporting rate for healthcare workers. Further, it might be helpful if other factors related to under-reporting be investigated in future studies.