In Germany, despite longstanding recommendations for influenza vaccination, uptake among health care workers (HCW) is poor. We conducted and evaluated a 2-year nationwide campaign to increase influenza vaccination rates among German HCW. The campaign was tailored to the results of a baseline survey and included the distribution of information material to all German hospitals (n approximately 2000) and engagement of stakeholders, such as professional HCW associations. Human and financial resources consisted of one full-time public health scientist (2 months) and approximately USD 45,000 to produce and distribute materials. We evaluated the intervention in a survey among a systematic sample of HCW in a sample of selected 20 hospitals. HCW were stratified by profession and asked to self-administer a questionnaire inquiring about self-perceived risk for influenza, belief of effectiveness of the vaccine, and influenza vaccination before the starting season (2003/2004) as well as the previous two seasons (2001/2002, 2002/2003). Three hundred and ninety-six of 800 (50%) HCW who were addressed in the evaluated hospitals participated in the evaluation survey. The overall influenza vaccination rate among respondents increased from 21% (2001/2002) to 26% (2003/2004), which was mostly due to a significant increase among physicians (2001/2002: 21%; 2003/2004: 31%; nurses: 20% and 22%, respectively). Significantly more physicians than nurses felt at increased risk for influenza and believed that the vaccine is very effective. Increased uptake among physicians (compared to nurses) was likely due to physicians' higher awareness of their risk and trust in the vaccine. In the future it may be necessary to address nurses differently than physicians. We conclude that a national campaign with very limited resources is feasible and capable of achieving measurable results in a short time frame.