On November 1, 2009, Taiwan began a nationwide pandemic A(H1N1) 2009 vaccine ("H1N1 vaccine") program to control the influenza pandemic. Timely assessment of immunization safety during this mass vaccination campaign was a public health priority. Therefore, the government developed a national postlicensure safety surveillance strategy to identify and evaluate new, unexpected, or prioritized adverse events in recipients of H1N1 vaccine in near real-time. We describe the design and methodology of this new safety assessment infrastructure, address challenges encountered, and its potential future use for routine vaccine pharmacovigilance in Taiwan.