Health care workers (HCWs) are at high risk of exposure to blood-bone viruses, especially through contaminated sharp injury. Objectives: This study was aimed to find out the associfltion between HCWs' sharp injuries and their risk of getting an occupational hepatitis B. Methods: A case-control study was carried out in 2007 with a total sample of 232 HCWs, including 63 cases and 169 controls in 13 health facilities in Nam Dinh and Ha Noi. Information on HBV risk factors was collected through direct interviews with structured questionnaires and analyzed to determine differences between the 2 groups. Results: The rate of sharp injured HCWs at work was considerably high (96.8 percent in case and 88.2 percent in control group). It was shown that sharp injured HCWs were at risk 4.1 times higher than non-injured ones (95 percent Ct: 1.2 - 37.0) with P 0.05. Those whose skins had been chapped/bled by sharps were at risk 3.1 times higher than those whose skins had been only peeled off (95 percent Ct: 1.2 - 9.5) with P 0.01. HCWs using gloves irregularly while working were at risk 1.3 times higher than who used gloves regularly. The results indicated that the factors increasing the risk of getting an occupational hepatitis B among sharp injured HCWs are the nature of the work, injury severity and utilization of safety and protection methods. Conclusions: The results are useful scientific evidences to recommend intervention programs to prevent infectious diseases for HCWs.